diff --git a/.changeset/little-ligers-hug.md b/.changeset/little-ligers-hug.md
new file mode 100644
index 000000000000..043b234f67f0
--- /dev/null
+++ b/.changeset/little-ligers-hug.md
@@ -0,0 +1,6 @@
+---
+"@rocket.chat/meteor": patch
+"@rocket.chat/model-typings": patch
+---
+
+fix: Dept w/o any BH config do not adhere to the default BH rules.
diff --git a/apps/meteor/ee/app/livechat-enterprise/server/business-hour/Helper.ts b/apps/meteor/ee/app/livechat-enterprise/server/business-hour/Helper.ts
index bd7ffdfedd43..b2e748356174 100644
--- a/apps/meteor/ee/app/livechat-enterprise/server/business-hour/Helper.ts
+++ b/apps/meteor/ee/app/livechat-enterprise/server/business-hour/Helper.ts
@@ -21,9 +21,31 @@ const getAllAgentIdsWithoutDepartment = async (): Promise<string[]> => {
 	return agentIdsWithoutDepartment;
 };
 
+const getAllAgentIdsWithDepartmentNotConnectedToBusinessHour = async (): Promise<string[]> => {
+	const activeDepartmentsWithoutBusinessHour = (
+		await LivechatDepartment.findActiveDepartmentsWithoutBusinessHour({
+			projection: { _id: 1 },
+		}).toArray()
+	).map((dept) => dept._id);
+
+	const agentIdsWithDepartmentNotConnectedToBusinessHour = await LivechatDepartmentAgents.findAllAgentsConnectedToListOfDepartments(
+		activeDepartmentsWithoutBusinessHour,
+	);
+	return agentIdsWithDepartmentNotConnectedToBusinessHour;
+};
+
+const getAllAgentIdsForDefaultBusinessHour = async (): Promise<string[]> => {
+	const [withoutDepartment, withDepartmentNotConnectedToBusinessHour] = await Promise.all([
+		getAllAgentIdsWithoutDepartment(),
+		getAllAgentIdsWithDepartmentNotConnectedToBusinessHour(),
+	]);
+
+	return [...new Set([...withoutDepartment, ...withDepartmentNotConnectedToBusinessHour])];
+};
+
 const getAgentIdsToHandle = async (businessHour: Record<string, any>): Promise<string[]> => {
 	if (businessHour.type === LivechatBusinessHourTypes.DEFAULT) {
-		return getAllAgentIdsWithoutDepartment();
+		return getAllAgentIdsForDefaultBusinessHour();
 	}
 	const departmentIds = (
 		await LivechatDepartment.findEnabledByBusinessHourId(businessHour._id, {
diff --git a/apps/meteor/server/models/raw/LivechatDepartment.ts b/apps/meteor/server/models/raw/LivechatDepartment.ts
index debe262060fe..75329e3e6125 100644
--- a/apps/meteor/server/models/raw/LivechatDepartment.ts
+++ b/apps/meteor/server/models/raw/LivechatDepartment.ts
@@ -128,6 +128,14 @@ export class LivechatDepartmentRaw extends BaseRaw<ILivechatDepartment> implemen
 		return this.find(query, options);
 	}
 
+	findActiveDepartmentsWithoutBusinessHour(options: FindOptions<ILivechatDepartment>): FindCursor<ILivechatDepartment> {
+		const query = {
+			enabled: true,
+			businessHourId: { $exists: false },
+		};
+		return this.find(query, options);
+	}
+
 	findEnabledByListOfBusinessHourIdsAndDepartmentIds(
 		businessHourIds: string[],
 		departmentIds: string[],
diff --git a/apps/meteor/server/models/raw/LivechatDepartmentAgents.ts b/apps/meteor/server/models/raw/LivechatDepartmentAgents.ts
index ace8ee052549..da709ff1136e 100644
--- a/apps/meteor/server/models/raw/LivechatDepartmentAgents.ts
+++ b/apps/meteor/server/models/raw/LivechatDepartmentAgents.ts
@@ -356,6 +356,10 @@ export class LivechatDepartmentAgentsRaw extends BaseRaw<ILivechatDepartmentAgen
 	countByDepartmentId(departmentId: string): Promise<number> {
 		return this.col.countDocuments({ departmentId });
 	}
+
+	findAllAgentsConnectedToListOfDepartments(departmentIds: string[]): Promise<string[]> {
+		return this.col.distinct('agentId', { departmentId: { $in: departmentIds } });
+	}
 }
 
 const isStringValue = (value: any): value is string => typeof value === 'string';
diff --git a/packages/model-typings/src/models/ILivechatDepartmentAgentsModel.ts b/packages/model-typings/src/models/ILivechatDepartmentAgentsModel.ts
index 081b1071c095..94c824e14f07 100644
--- a/packages/model-typings/src/models/ILivechatDepartmentAgentsModel.ts
+++ b/packages/model-typings/src/models/ILivechatDepartmentAgentsModel.ts
@@ -87,4 +87,5 @@ export interface ILivechatDepartmentAgentsModel extends IBaseModel<ILivechatDepa
 	getNextBotForDepartment(departmentId: string, ignoreAgentId?: string): Promise<{ agentId: string; username: string } | undefined>;
 	replaceUsernameOfAgentByUserId(userId: string, username: string): Promise<UpdateResult | Document>;
 	countByDepartmentId(departmentId: string): Promise<number>;
+	findAllAgentsConnectedToListOfDepartments(departmentIds: string[]): Promise<string[]>;
 }
diff --git a/packages/model-typings/src/models/ILivechatDepartmentModel.ts b/packages/model-typings/src/models/ILivechatDepartmentModel.ts
index 31e122e7e1f5..d0f11f2bff95 100644
--- a/packages/model-typings/src/models/ILivechatDepartmentModel.ts
+++ b/packages/model-typings/src/models/ILivechatDepartmentModel.ts
@@ -23,6 +23,8 @@ export interface ILivechatDepartmentModel extends IBaseModel<ILivechatDepartment
 		options: FindOptions<ILivechatDepartment>,
 	): FindCursor<ILivechatDepartment>;
 
+	findActiveDepartmentsWithoutBusinessHour(options: FindOptions<ILivechatDepartment>): FindCursor<ILivechatDepartment>;
+
 	addBusinessHourToDepartmentsByIds(ids: string[], businessHourId: string): Promise<Document | UpdateResult>;
 
 	removeBusinessHourFromDepartmentsByIdsAndBusinessHourId(ids: string[], businessHourId: string): Promise<Document | UpdateResult>;