diff --git a/ee/app/assets/javascripts/security_dashboard/components/filter.vue b/ee/app/assets/javascripts/security_dashboard/components/filter.vue
index e848f3915f0c21f480949948bb1047e812d69a94..59328d6b495a1e47dc316b07d14545d3476a12c2 100644
--- a/ee/app/assets/javascripts/security_dashboard/components/filter.vue
+++ b/ee/app/assets/javascripts/security_dashboard/components/filter.vue
@@ -1,12 +1,12 @@
 <script>
 import { mapGetters, mapActions } from 'vuex';
-import { GlDropdown, GlDropdownItem } from '@gitlab/ui';
+import { GlDropdown, GlSearchBoxByType } from '@gitlab/ui';
 import Icon from '~/vue_shared/components/icon.vue';
 
 export default {
   components: {
     GlDropdown,
-    GlDropdownItem,
+    GlSearchBoxByType,
     Icon,
   },
   props: {
@@ -15,6 +15,11 @@ export default {
       required: true,
     },
   },
+  data() {
+    return {
+      filterTerm: '',
+    };
+  },
   computed: {
     ...mapGetters('filters', ['getFilter', 'getSelectedOptions', 'getSelectedOptionNames']),
     filter() {
@@ -26,6 +31,11 @@ export default {
     selectedOptionText() {
       return this.getSelectedOptionNames(this.filterId) || '-';
     },
+    filteredOptions() {
+      return this.filter.options.filter(option =>
+        option.name.toLowerCase().includes(this.filterTerm.toLowerCase()),
+      );
+    },
   },
   methods: {
     ...mapActions('filters', ['setFilter']),
@@ -38,6 +48,9 @@ export default {
     isSelected(option) {
       return this.selection.has(option.id);
     },
+    closeDropdown(event) {
+      this.$root.$emit('clicked::link', event);
+    },
   },
 };
 </script>
@@ -45,7 +58,7 @@ export default {
 <template>
   <div class="dashboard-filter">
     <strong class="js-name">{{ filter.name }}</strong>
-    <gl-dropdown class="d-block mt-1">
+    <gl-dropdown class="d-block mt-1" menu-class="dropdown-extended-height">
       <template slot="button-content">
         <span class="text-truncate">
           {{ selectedOptionText.firstOption }}
@@ -57,20 +70,56 @@ export default {
         <i class="fa fa-chevron-down" aria-hidden="true"></i>
       </template>
 
-      <gl-dropdown-item
-        v-for="option in filter.options"
-        :key="option.id"
-        @click="clickFilter(option)"
+      <div class="dropdown-title mb-0">
+        {{ filter.name }}
+        <button
+          ref="close"
+          class="btn-blank float-right"
+          type="button"
+          :aria-label="__('Close')"
+          @click="closeDropdown"
+        >
+          <icon name="close" aria-hidden="true" class="vertical-align-middle" />
+        </button>
+      </div>
+
+      <gl-search-box-by-type
+        v-if="filter.options.length >= 20"
+        ref="searchBox"
+        v-model="filterTerm"
+        class="m-2"
+        :placeholder="__('Filter...')"
+      />
+
+      <div :class="{ 'dropdown-content': filterId === 'project_id' }">
+        <button
+          v-for="option in filteredOptions"
+          :key="option.id"
+          role="menuitem"
+          type="button"
+          class="dropdown-item"
+          @click="clickFilter(option)"
+        >
+          <span class="d-flex">
+            <icon
+              v-if="isSelected(option)"
+              class="flex-shrink-0 js-check"
+              name="mobile-issue-close"
+            />
+            <span :class="isSelected(option) ? 'prepend-left-4' : 'prepend-left-20'">{{
+              option.name
+            }}</span>
+          </span>
+        </button>
+      </div>
+
+      <button
+        v-if="filteredOptions.length === 0"
+        type="button"
+        class="dropdown-item no-pointer-events text-secondary"
       >
-        <icon
-          v-if="isSelected(option)"
-          class="vertical-align-middle js-check"
-          name="mobile-issue-close"
-        />
-        <span class="vertical-align-middle" :class="{ 'prepend-left-20': !isSelected(option) }">{{
-          option.name
-        }}</span>
-      </gl-dropdown-item>
+        {{ __('No matching results') }}
+      </button>
     </gl-dropdown>
   </div>
 </template>
diff --git a/ee/app/assets/javascripts/security_dashboard/store/moderator.js b/ee/app/assets/javascripts/security_dashboard/store/moderator.js
index 0d3acab79e919fe23a0ac547a1947685f0edc4cb..b84d20891cdda7e45008123082453ab7b6b31547 100644
--- a/ee/app/assets/javascripts/security_dashboard/store/moderator.js
+++ b/ee/app/assets/javascripts/security_dashboard/store/moderator.js
@@ -1,6 +1,7 @@
 import * as vulnerabilitiesMutationTypes from './modules/vulnerabilities/mutation_types';
 import * as filtersMutationTypes from './modules/filters/mutation_types';
 import * as projectsMutationTypes from './modules/projects/mutation_types';
+import { BASE_FILTERS } from './modules/filters/constants';
 
 export default function configureModerator(store) {
   store.$router.beforeEach((to, from, next) => {
@@ -19,10 +20,7 @@ export default function configureModerator(store) {
         store.dispatch('filters/setFilterOptions', {
           filterId: 'project_id',
           options: [
-            {
-              name: 'All',
-              id: 'all',
-            },
+            BASE_FILTERS.project_id,
             ...payload.projects.map(project => ({
               name: project.name,
               id: project.id.toString(),
diff --git a/ee/app/assets/javascripts/security_dashboard/store/modules/filters/constants.js b/ee/app/assets/javascripts/security_dashboard/store/modules/filters/constants.js
index 28b508d12a2a1bd2c0bab2dfa32b8a19948d5f75..fcde0a8d93ee53b8de82c19ab55cf8fa7f8e9d32 100644
--- a/ee/app/assets/javascripts/security_dashboard/store/modules/filters/constants.js
+++ b/ee/app/assets/javascripts/security_dashboard/store/modules/filters/constants.js
@@ -27,3 +27,18 @@ export const REPORT_TYPES = {
   dependency_scanning: s__('ciReport|Dependency Scanning'),
   sast: s__('ciReport|SAST'),
 };
+
+export const BASE_FILTERS = {
+  severity: {
+    name: s__('ciReport|All severities'),
+    id: 'all',
+  },
+  report_type: {
+    name: s__('ciReport|All report types'),
+    id: 'all',
+  },
+  project_id: {
+    name: s__('ciReport|All projects'),
+    id: 'all',
+  },
+};
diff --git a/ee/app/assets/javascripts/security_dashboard/store/modules/filters/state.js b/ee/app/assets/javascripts/security_dashboard/store/modules/filters/state.js
index 446be736b95bf420ca16d52cc0c8e04260145c15..f84bb0a836f6ed6bf5053c7c90471090c8f1dc5f 100644
--- a/ee/app/assets/javascripts/security_dashboard/store/modules/filters/state.js
+++ b/ee/app/assets/javascripts/security_dashboard/store/modules/filters/state.js
@@ -1,46 +1,25 @@
-import { SEVERITY_LEVELS, REPORT_TYPES } from './constants';
+import { SEVERITY_LEVELS, REPORT_TYPES, BASE_FILTERS } from './constants';
+
+const optionsObjectToArray = obj => Object.entries(obj).map(([id, name]) => ({ id, name }));
 
 export default () => ({
   filters: [
     {
       name: 'Severity',
       id: 'severity',
-      options: [
-        {
-          name: 'All',
-          id: 'all',
-        },
-        ...Object.entries(SEVERITY_LEVELS).map(severity => {
-          const [id, name] = severity;
-          return { id, name };
-        }),
-      ],
+      options: [BASE_FILTERS.severity, ...optionsObjectToArray(SEVERITY_LEVELS)],
       selection: new Set(['all']),
     },
     {
       name: 'Report type',
       id: 'report_type',
-      options: [
-        {
-          name: 'All',
-          id: 'all',
-        },
-        ...Object.entries(REPORT_TYPES).map(type => {
-          const [id, name] = type;
-          return { id, name };
-        }),
-      ],
+      options: [BASE_FILTERS.report_type, ...optionsObjectToArray(REPORT_TYPES)],
       selection: new Set(['all']),
     },
     {
       name: 'Project',
       id: 'project_id',
-      options: [
-        {
-          name: 'All',
-          id: 'all',
-        },
-      ],
+      options: [BASE_FILTERS.project_id],
       selection: new Set(['all']),
     },
   ],
diff --git a/ee/changelogs/unreleased/9253-add-full-feature-dropdowns-to-group-security-dashboard-filters.yml b/ee/changelogs/unreleased/9253-add-full-feature-dropdowns-to-group-security-dashboard-filters.yml
new file mode 100644
index 0000000000000000000000000000000000000000..021be46b1f94d0635ebf592df969880f59ffdd96
--- /dev/null
+++ b/ee/changelogs/unreleased/9253-add-full-feature-dropdowns-to-group-security-dashboard-filters.yml
@@ -0,0 +1,5 @@
+---
+title: Make editing the filters in the Group Security Dashboard easier.
+merge_request: 10138
+author:
+type: fixed
diff --git a/ee/spec/frontend/security_dashboard/store/filters/getters_spec.js b/ee/spec/frontend/security_dashboard/store/filters/getters_spec.js
index 0fc6fb6a2d5c57cb3bba1ef51fdb12f227b04c95..8f6e131188f7a6a62fdd35c09194bf9e508b7df4 100644
--- a/ee/spec/frontend/security_dashboard/store/filters/getters_spec.js
+++ b/ee/spec/frontend/security_dashboard/store/filters/getters_spec.js
@@ -1,5 +1,6 @@
 import createState from 'ee/security_dashboard/store/modules/filters/state';
 import * as getters from 'ee/security_dashboard/store/modules/filters/getters';
+import { BASE_FILTERS } from 'ee/security_dashboard/store/modules/filters/constants';
 
 describe('filters module getters', () => {
   const mockedGetters = state => {
@@ -28,13 +29,13 @@ describe('filters module getters', () => {
 
   describe('getSelectedOptions', () => {
     describe('with one selected option', () => {
-      it('should return "All" as the selected option', () => {
+      it('should return the base filter as the selected option', () => {
         const selectedOptions = getters.getSelectedOptions(state, mockedGetters(state))(
           'report_type',
         );
 
         expect(selectedOptions).toHaveLength(1);
-        expect(selectedOptions[0].name).toEqual('All');
+        expect(selectedOptions[0].name).toBe(BASE_FILTERS.report_type.name);
       });
     });
 
@@ -57,12 +58,13 @@ describe('filters module getters', () => {
   });
 
   describe('getSelectedOptionNames', () => {
-    it('should return "All" as the selected option', () => {
+    it('should return the base filter as the selected option', () => {
       const selectedOptionNames = getters.getSelectedOptionNames(state, mockedGetters(state))(
         'severity',
       );
 
-      expect(selectedOptionNames).toEqual({ firstOption: 'All', extraOptionCount: '' });
+      expect(selectedOptionNames.firstOption).toBe(BASE_FILTERS.severity.name);
+      expect(selectedOptionNames.extraOptionCount).toBe('');
     });
 
     it('should return the correct message when multiple filters are selected', () => {
diff --git a/ee/spec/javascripts/security_dashboard/components/filter_spec.js b/ee/spec/javascripts/security_dashboard/components/filter_spec.js
index 82312bbe8989d55b90b3f1144e80f30e508cd4d9..4b74fd64e232f3c01bb0ee2a6bf981c08b5502dd 100644
--- a/ee/spec/javascripts/security_dashboard/components/filter_spec.js
+++ b/ee/spec/javascripts/security_dashboard/components/filter_spec.js
@@ -6,8 +6,36 @@ import { mountComponentWithStore } from 'spec/helpers/vue_mount_component_helper
 describe('Filter component', () => {
   let vm;
   let props;
-  const store = createStore();
-  const Component = Vue.extend(component);
+  let store;
+  let Component;
+
+  function isDropdownOpen() {
+    const toggleButton = vm.$el.querySelector('.dropdown-toggle');
+    return toggleButton.getAttribute('aria-expanded') === 'true';
+  }
+
+  function setProjectsCount(count) {
+    const projects = new Array(count).fill(null).map((_, i) => ({
+      name: i.toString(),
+      id: i.toString(),
+    }));
+
+    store.dispatch('filters/setFilterOptions', {
+      filterId: 'project_id',
+      options: projects,
+    });
+  }
+
+  const findSearchInput = () => vm.$refs.searchBox && vm.$refs.searchBox.$el.querySelector('input');
+
+  beforeEach(() => {
+    store = createStore();
+    Component = Vue.extend(component);
+  });
+
+  afterEach(() => {
+    vm.$destroy();
+  });
 
   describe('severity', () => {
     beforeEach(() => {
@@ -15,10 +43,6 @@ describe('Filter component', () => {
       vm = mountComponentWithStore(Component, { store, props });
     });
 
-    afterEach(() => {
-      vm.$destroy();
-    });
-
     it('should display all 8 severity options', () => {
       expect(vm.$el.querySelectorAll('.dropdown-item').length).toEqual(8);
     });
@@ -30,5 +54,68 @@ describe('Filter component', () => {
     it('should display "Severity" as the option name', () => {
       expect(vm.$el.querySelector('.js-name').textContent).toContain('Severity');
     });
+
+    it('should not have a search box', () => {
+      expect(findSearchInput()).not.toEqual(jasmine.any(HTMLElement));
+    });
+
+    it('should not be open', () => {
+      expect(isDropdownOpen()).toBe(false);
+    });
+
+    describe('when the dropdown is open', () => {
+      beforeEach(done => {
+        vm.$el.querySelector('.dropdown-toggle').click();
+        vm.$nextTick(done);
+      });
+
+      it('should keep the menu open after clicking on an item', done => {
+        expect(isDropdownOpen()).toBe(true);
+        vm.$el.querySelector('.dropdown-item').click();
+        vm.$nextTick(() => {
+          expect(isDropdownOpen()).toBe(true);
+          done();
+        });
+      });
+
+      it('should close the menu when the close button is clicked', done => {
+        expect(isDropdownOpen()).toBe(true);
+        vm.$refs.close.click();
+        vm.$nextTick(() => {
+          expect(isDropdownOpen()).toBe(false);
+          done();
+        });
+      });
+    });
+  });
+
+  describe('Project', () => {
+    describe('when there are lots of projects', () => {
+      const lots = 30;
+      beforeEach(done => {
+        props = { filterId: 'project_id', dashboardDocumentation: '' };
+        vm = mountComponentWithStore(Component, { store, props });
+        setProjectsCount(lots);
+        vm.$nextTick(done);
+      });
+
+      it('should display a search box', () => {
+        expect(findSearchInput()).toEqual(jasmine.any(HTMLElement));
+      });
+
+      it(`should show all projects`, () => {
+        expect(vm.$el.querySelectorAll('.dropdown-item').length).toBe(lots);
+      });
+
+      it('should show only matching projects when a search term is entered', done => {
+        const input = findSearchInput();
+        input.value = '0';
+        input.dispatchEvent(new Event('input'));
+        vm.$nextTick(() => {
+          expect(vm.$el.querySelectorAll('.dropdown-item').length).toBe(3);
+          done();
+        });
+      });
+    });
   });
 });
diff --git a/ee/spec/javascripts/security_dashboard/store/moderator_spec.js b/ee/spec/javascripts/security_dashboard/store/moderator_spec.js
index e6c05a0a969033147aac43532a05d64e8ba3318b..d47a551175dd5652810468efcd6a15f0d6981df7 100644
--- a/ee/spec/javascripts/security_dashboard/store/moderator_spec.js
+++ b/ee/spec/javascripts/security_dashboard/store/moderator_spec.js
@@ -2,6 +2,7 @@ import createStore from 'ee/security_dashboard/store/index';
 import * as projectsMutationTypes from 'ee/security_dashboard/store/modules/projects/mutation_types';
 import * as filtersMutationTypes from 'ee/security_dashboard/store/modules/filters/mutation_types';
 import * as vulnerabilitiesMutationTypes from 'ee/security_dashboard/store/modules/vulnerabilities/mutation_types';
+import { BASE_FILTERS } from 'ee/security_dashboard/store/modules/filters/constants';
 
 describe('moderator', () => {
   let store;
@@ -22,7 +23,7 @@ describe('moderator', () => {
       'filters/setFilterOptions',
       Object({
         filterId: 'project_id',
-        options: [{ name: 'All', id: 'all' }, { name: 'foo', id: '1' }],
+        options: [BASE_FILTERS.project_id, { name: 'foo', id: '1' }],
       }),
     );
   });
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index af10e123ee18566d2c73fea09c44838c83e12e75..a71f5fd9f8204e486bc218fb0bd48ce26cc915e4 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -12392,6 +12392,15 @@ msgstr ""
 msgid "ciReport|(is loading, errors when loading results)"
 msgstr ""
 
+msgid "ciReport|All projects"
+msgstr ""
+
+msgid "ciReport|All report types"
+msgstr ""
+
+msgid "ciReport|All severities"
+msgstr ""
+
 msgid "ciReport|Class"
 msgstr ""