diff --git a/packages/backend/src/core/FanoutTimelineEndpointService.ts b/packages/backend/src/core/FanoutTimelineEndpointService.ts
index befbff43e4..af0b7f0e20 100644
--- a/packages/backend/src/core/FanoutTimelineEndpointService.ts
+++ b/packages/backend/src/core/FanoutTimelineEndpointService.ts
@@ -41,7 +41,8 @@ type TimelineOptions = {
 	excludeReplies?: boolean;
 	excludePureRenotes: boolean;
 	ignoreAuthorFromUserSuspension?: boolean;
-	includeMutedChannels?: boolean;
+	/** @default true */
+	excludeMutedChannels?: boolean;
 	dbFallback: (untilId: string | null, sinceId: string | null, limit: number) => Promise<MiNote[]>,
 };
 
@@ -121,7 +122,7 @@ export class FanoutTimelineEndpointService {
 					this.cacheService.renoteMutingsCache.fetch(ps.me.id),
 					this.cacheService.userBlockedCache.fetch(ps.me.id),
 					this.cacheService.userProfileCache.fetch(me.id).then(p => new Set(p.mutedInstances)),
-					ps.includeMutedChannels ? Promise.resolve(new Set<string>()) : this.channelMutingService.mutingChannelsCache.fetch(me.id),
+					(ps.excludeMutedChannels ?? true) ? this.channelMutingService.mutingChannelsCache.fetch(me.id) : Promise.resolve(new Set<string>()),
 				]);
 
 				const parentFilter = filter;
@@ -132,7 +133,7 @@ export class FanoutTimelineEndpointService {
 					if (isUserRelated(note.renote, userIdsWhoMeMuting, ps.ignoreAuthorFromMute)) return false;
 					if (!ps.ignoreAuthorFromMute && isRenote(note) && !isQuote(note) && userIdsWhoMeMutingRenotes.has(note.userId)) return false;
 					if (isInstanceMuted(note, userMutedInstances)) return false;
-					if (!ps.includeMutedChannels && isChannelRelated(note, userMutedChannels)) return false;
+					if ((ps.excludeMutedChannels ?? true) && isChannelRelated(note, userMutedChannels)) return false;
 
 					return parentFilter(note);
 				};
diff --git a/packages/backend/src/server/api/endpoints/channels/timeline.ts b/packages/backend/src/server/api/endpoints/channels/timeline.ts
index 3c55df4c67..78fdfb7476 100644
--- a/packages/backend/src/server/api/endpoints/channels/timeline.ts
+++ b/packages/backend/src/server/api/endpoints/channels/timeline.ts
@@ -104,7 +104,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				useDbFallback: true,
 				redisTimelines: [`channelTimeline:${channel.id}`],
 				excludePureRenotes: false,
-				includeMutedChannels: true,
+				excludeMutedChannels: false,
 				noteFilter: note => {
 					// 共通機能を使うと見ているチャンネルそのものもミュートしてしまうので閲覧中のチャンネル以外を除く形にする
 					if (note.channelId === channel.id && (note.renoteChannelId === null || note.renoteChannelId === channel.id)) return true;