diff --git a/packages/primevue/src/listbox/Listbox.spec.js b/packages/primevue/src/listbox/Listbox.spec.js
index 23084674c..4bf70bdd7 100644
--- a/packages/primevue/src/listbox/Listbox.spec.js
+++ b/packages/primevue/src/listbox/Listbox.spec.js
@@ -47,5 +47,70 @@ describe('Listbox.vue', () => {
 
             expect(icon.classes()).toContain('pi-discord');
         });
+
+        it('should correctly filter', async () => {
+            await wrapper.setProps({
+                filter: true
+            });
+
+            const filterInput = wrapper.find('input.p-listbox-filter');
+
+            expect(filterInput.exists()).toBe(true);
+
+            await filterInput.setValue('is');
+
+            const options = wrapper.findAll('.p-listbox-option');
+
+            expect(options.length).toBe(2);
+            expect(options[0].text()).toBe('Istanbul');
+        });
+
+        it('should correctly filter groups', async () => {
+            await wrapper.setProps({
+                filter: true,
+                optionGroupLabel: 'label',
+                optionLabel: 'label',
+                optionGroupChildren: 'items',
+                options: [
+                    {
+                        label: 'Germany',
+                        code: 'DE',
+                        items: [
+                            { label: 'Berlin', value: 'Berlin' },
+                            { label: 'Frankfurt', value: 'Frankfurt' },
+                            { label: 'Hamburg', value: 'Hamburg' },
+                            { label: 'Munich', value: 'Munich' }
+                        ]
+                    },
+                    {
+                        label: 'USA',
+                        code: 'US',
+                        items: [
+                            { label: 'Chicago', value: 'Chicago' },
+                            { label: 'Los Angeles', value: 'Los Angeles' },
+                            { label: 'New York', value: 'New York' },
+                            { label: 'San Francisco', value: 'San Francisco' }
+                        ]
+                    }
+                ]
+            });
+
+            const filterInput = wrapper.find('input.p-listbox-filter');
+
+            expect(filterInput.exists()).toBe(true);
+
+            await filterInput.setValue('ch');
+
+            const optionGroups = wrapper.findAll('.p-listbox-option-group');
+            const options = wrapper.findAll('.p-listbox-option');
+
+            expect(optionGroups.length).toBe(2);
+            expect(optionGroups[0].text()).toBe('Germany');
+            expect(optionGroups[1].text()).toBe('USA');
+
+            expect(options.length).toBe(2);
+            expect(options[0].text()).toBe('Munich');
+            expect(options[1].text()).toBe('Chicago');
+        });
     });
 });
diff --git a/packages/primevue/src/listbox/Listbox.vue b/packages/primevue/src/listbox/Listbox.vue
index 33b69bf4a..3683882a4 100755
--- a/packages/primevue/src/listbox/Listbox.vue
+++ b/packages/primevue/src/listbox/Listbox.vue
@@ -703,17 +703,6 @@ export default {
             this.writeValue(value, event);
             this.$emit('change', { originalEvent: event, value });
         },
-        flatOptions(options) {
-            return (options || []).reduce((result, option, index) => {
-                result.push({ optionGroup: option, group: true, index });
-
-                const optionGroupChildren = this.getOptionGroupChildren(option);
-
-                optionGroupChildren && optionGroupChildren.forEach((o) => result.push(o));
-
-                return result;
-            }, []);
-        },
         listRef(el, contentRef) {
             this.list = el;
             contentRef && contentRef(el); // For VirtualScroller
@@ -723,10 +712,25 @@ export default {
         }
     },
     computed: {
-        visibleOptions() {
-            const options = this.optionGroupLabel ? this.flatOptions(this.options) : this.options || [];
+        optionsListFlat() {
+            return this.filterValue ? FilterService.filter(this.options, this.searchFields, this.filterValue, this.filterMatchMode, this.filterLocale) : this.options;
+        },
+        optionsListGroup() {
+            const filteredOptions = [];
 
-            return this.filterValue ? FilterService.filter(options, this.searchFields, this.filterValue, this.filterMatchMode, this.filterLocale) : options;
+            (this.options || []).forEach((optionGroup) => {
+                const optionGroupChildren = this.getOptionGroupChildren(optionGroup) || [];
+                const filteredChildren = this.filterValue ? FilterService.filter(optionGroupChildren, this.searchFields, this.filterValue, this.filterMatchMode, this.filterLocale) : optionGroupChildren;
+
+                if (filteredChildren?.length) {
+                    filteredOptions.push({ optionGroup, group: true }, ...filteredChildren);
+                }
+            });
+
+            return filteredOptions;
+        },
+        visibleOptions() {
+            return this.optionGroupLabel ? this.optionsListGroup : this.optionsListFlat;
         },
         // @deprecated use $filled instead
         hasSelectedOption() {