diff --git a/packages/block-editor/src/components/inserter/block-list.js b/packages/block-editor/src/components/inserter/block-list.js
index a1aafcd54061de..26ad6229546530 100644
--- a/packages/block-editor/src/components/inserter/block-list.js
+++ b/packages/block-editor/src/components/inserter/block-list.js
@@ -4,7 +4,6 @@
 import {
 	map,
 	includes,
-	filter,
 	findIndex,
 	flow,
 	sortBy,
@@ -119,20 +118,25 @@ function InserterBlockList( {
 	}, [ filterValue, items, categories, collections ] );
 
 	const childItems = useMemo( () => {
-		return filter( filteredItems, ( { name } ) =>
+		return filteredItems.filter( ( { name } ) =>
 			includes( rootChildBlocks, name )
 		);
 	}, [ filteredItems, rootChildBlocks ] );
 
 	const suggestedItems = useMemo( () => {
-		return filter( items, ( item ) => item.utility > 0 ).slice(
-			0,
-			MAX_SUGGESTED_ITEMS
-		);
+		return items
+			.filter( ( item ) => item.utility > 0 )
+			.slice( 0, MAX_SUGGESTED_ITEMS );
 	}, [ items ] );
 
 	const reusableItems = useMemo( () => {
-		return filter( filteredItems, { category: 'reusable' } );
+		return filteredItems.filter(
+			( { category } ) => category === 'reusable'
+		);
+	}, [ filteredItems ] );
+
+	const uncategorizedItems = useMemo( () => {
+		return filteredItems.filter( ( item ) => ! item.category );
 	}, [ filteredItems ] );
 
 	const itemsPerCategory = useMemo( () => {
@@ -145,7 +149,9 @@ function InserterBlockList( {
 
 		return flow(
 			( itemList ) =>
-				filter( itemList, ( item ) => item.category !== 'reusable' ),
+				itemList.filter(
+					( item ) => item.category && item.category !== 'reusable'
+				),
 			( itemList ) => sortBy( itemList, getCategoryIndex ),
 			( itemList ) => groupBy( itemList, 'category' )
 		)( filteredItems );
@@ -228,6 +234,19 @@ function InserterBlockList( {
 					);
 				} ) }
 
+			{ ! hasChildItems && !! uncategorizedItems.length && (
+				<InserterPanel
+					className="block-editor-inserter__uncategorized-blocks-panel"
+					title={ __( 'Uncategorized' ) }
+				>
+					<BlockTypesList
+						items={ uncategorizedItems }
+						onSelect={ onSelectItem }
+						onHover={ onHover }
+					/>
+				</InserterPanel>
+			) }
+
 			{ ! hasChildItems &&
 				map( collections, ( collection, namespace ) => {
 					const collectionItems = itemsPerCollection[ namespace ];
diff --git a/packages/blocks/src/api/registration.js b/packages/blocks/src/api/registration.js
index 6b165502173feb..d20af322af4fd2 100644
--- a/packages/blocks/src/api/registration.js
+++ b/packages/blocks/src/api/registration.js
@@ -1,4 +1,4 @@
-/* eslint no-console: [ 'error', { allow: [ 'error' ] } ] */
+/* eslint no-console: [ 'error', { allow: [ 'error', 'warn' ] } ] */
 
 /**
  * External dependencies
@@ -203,20 +203,20 @@ export function registerBlockType( name, settings ) {
 		console.error( 'The "edit" property must be a valid function.' );
 		return;
 	}
-	if ( ! ( 'category' in settings ) ) {
-		console.error( 'The block "' + name + '" must have a category.' );
-		return;
-	}
 	if (
 		'category' in settings &&
 		! some( select( 'core/blocks' ).getCategories(), {
 			slug: settings.category,
 		} )
 	) {
-		console.error(
-			'The block "' + name + '" must have a registered category.'
+		console.warn(
+			'The block "' +
+				name +
+				'" is registered with an invalid category "' +
+				settings.category +
+				'".'
 		);
-		return;
+		delete settings.category;
 	}
 	if ( ! ( 'title' in settings ) || settings.title === '' ) {
 		console.error( 'The block "' + name + '" must have a title.' );
diff --git a/packages/blocks/src/api/test/registration.js b/packages/blocks/src/api/test/registration.js
index d61b6501ae2d1c..08e4c11153e347 100644
--- a/packages/blocks/src/api/test/registration.js
+++ b/packages/blocks/src/api/test/registration.js
@@ -173,23 +173,7 @@ describe( 'blocks', () => {
 			expect( block ).toBeUndefined();
 		} );
 
-		it( 'should reject blocks without category', () => {
-			const blockType = {
-					settingName: 'settingValue',
-					save: noop,
-					title: 'block title',
-				},
-				block = registerBlockType(
-					'my-plugin/fancy-block-8',
-					blockType
-				);
-			expect( console ).toHaveErroredWith(
-				'The block "my-plugin/fancy-block-8" must have a category.'
-			);
-			expect( block ).toBeUndefined();
-		} );
-
-		it( 'should reject blocks with non registered category.', () => {
+		it( 'should unset category of blocks with non registered category.', () => {
 			const blockType = {
 					save: noop,
 					category: 'custom-category-slug',
@@ -199,10 +183,11 @@ describe( 'blocks', () => {
 					'my-plugin/fancy-block-9',
 					blockType
 				);
-			expect( console ).toHaveErroredWith(
-				'The block "my-plugin/fancy-block-9" must have a registered category.'
+			expect( console ).toHaveWarnedWith(
+				'The block "my-plugin/fancy-block-9" is registered with an invalid category "custom-category-slug".'
 			);
-			expect( block ).toBeUndefined();
+			expect( block ).not.toBeUndefined();
+			expect( block.category ).toBeUndefined();
 		} );
 
 		it( 'should reject blocks without title', () => {
diff --git a/packages/blocks/src/store/test/selectors.js b/packages/blocks/src/store/test/selectors.js
index 8ee2fd064bbff7..636228f7835acb 100644
--- a/packages/blocks/src/store/test/selectors.js
+++ b/packages/blocks/src/store/test/selectors.js
@@ -1,6 +1,8 @@
 /**
  * External dependencies
  */
+import { omit } from 'lodash';
+
 import deepFreeze from 'deep-freeze';
 
 /**
@@ -243,6 +245,7 @@ describe( 'selectors', () => {
 		describe.each( [
 			[ 'name', name ],
 			[ 'block type', blockType ],
+			[ 'block type without category', omit( blockType, 'category' ) ],
 		] )( 'by %s', ( label, nameOrType ) => {
 			it( 'should return false if not match', () => {
 				const result = isMatchingSearchTerm(
@@ -304,15 +307,17 @@ describe( 'selectors', () => {
 				expect( result ).toBe( true );
 			} );
 
-			it( 'should return true if match using the categories', () => {
-				const result = isMatchingSearchTerm(
-					state,
-					nameOrType,
-					'COMMON'
-				);
-
-				expect( result ).toBe( true );
-			} );
+			if ( nameOrType.category ) {
+				it( 'should return true if match using the categories', () => {
+					const result = isMatchingSearchTerm(
+						state,
+						nameOrType,
+						'COMMON'
+					);
+
+					expect( result ).toBe( true );
+				} );
+			}
 		} );
 	} );
 
diff --git a/packages/edit-post/src/components/manage-blocks-modal/category.js b/packages/edit-post/src/components/manage-blocks-modal/category.js
index 5df158fe254333..3169115c86b83b 100644
--- a/packages/edit-post/src/components/manage-blocks-modal/category.js
+++ b/packages/edit-post/src/components/manage-blocks-modal/category.js
@@ -19,7 +19,7 @@ import EditPostSettings from '../edit-post-settings';
 
 function BlockManagerCategory( {
 	instanceId,
-	category,
+	title,
 	blockTypes,
 	hiddenBlockTypes,
 	toggleVisible,
@@ -70,7 +70,7 @@ function BlockManagerCategory( {
 				onChange={ toggleAllVisible }
 				className="edit-post-manage-blocks-modal__category-title"
 				aria-checked={ ariaChecked }
-				label={ <span id={ titleId }>{ category.title }</span> }
+				label={ <span id={ titleId }>{ title }</span> }
 			/>
 			<BlockTypesChecklist
 				blockTypes={ filteredBlockTypes }
diff --git a/packages/edit-post/src/components/manage-blocks-modal/manager.js b/packages/edit-post/src/components/manage-blocks-modal/manager.js
index 41eba0b4f97e9a..f5922f8549bd44 100644
--- a/packages/edit-post/src/components/manage-blocks-modal/manager.js
+++ b/packages/edit-post/src/components/manage-blocks-modal/manager.js
@@ -76,12 +76,19 @@ function BlockManager( {
 				{ categories.map( ( category ) => (
 					<BlockManagerCategory
 						key={ category.slug }
-						category={ category }
+						title={ category.title }
 						blockTypes={ filter( blockTypes, {
 							category: category.slug,
 						} ) }
 					/>
 				) ) }
+				<BlockManagerCategory
+					title={ __( 'Uncategorized' ) }
+					blockTypes={ filter(
+						blockTypes,
+						( { category } ) => ! category
+					) }
+				/>
 			</div>
 		</div>
 	);