diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index 39f7886c54..74958f977e 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -1211,10 +1211,13 @@ fork_from_self = You cannot fork a repository you own.
 fork_guest_user = Sign in to fork this repository.
 watch_guest_user = Sign in to watch this repository.
 star_guest_user = Sign in to star this repository.
-unwatch = Unwatch
+subscribe.issue.guest.tooltip = Sign in to subscribe to this issue.
+subscribe.pull.guest.tooltip = Sign in to subscribe to this pull request.
+
 watch = Watch
-unstar = Unstar
+unwatch = Unwatch
 star = Star
+unstar = Unstar
 fork = Fork
 download_archive = Download repository
 more_operations = More operations
diff --git a/release-notes/8.0.0/4095.md b/release-notes/8.0.0/4095.md
new file mode 100644
index 0000000000..0f072b65c4
--- /dev/null
+++ b/release-notes/8.0.0/4095.md
@@ -0,0 +1 @@
+Disable Subscribe button for guest users.
diff --git a/templates/repo/issue/view_content/sidebar/watching.tmpl b/templates/repo/issue/view_content/sidebar/watching.tmpl
index 05936d090b..d3d75946b5 100644
--- a/templates/repo/issue/view_content/sidebar/watching.tmpl
+++ b/templates/repo/issue/view_content/sidebar/watching.tmpl
@@ -1,6 +1,13 @@
-<form hx-boost="true" hx-sync="this:replace" hx-target="this" method="post" action="{{.Issue.Link}}/watch">
+<form hx-boost="true" hx-sync="this:replace" hx-target="this" method="post" action="{{.Issue.Link}}/watch"
+	{{if not $.IsSigned}}
+		{{if $.Issue.IsPull}}
+			data-tooltip-content="{{ctx.Locale.Tr "repo.subscribe.pull.guest.tooltip"}}"
+		{{else}}
+			data-tooltip-content="{{ctx.Locale.Tr "repo.subscribe.issue.guest.tooltip"}}"
+		{{end}}
+	{{end}}>
 	<input type="hidden" name="watch" value="{{if $.IssueWatch.IsWatching}}0{{else}}1{{end}}">
-	<button class="fluid ui button">
+	<button class="fluid ui button {{if not $.IsSigned}}disabled{{end}}">
 		{{if $.IssueWatch.IsWatching}}
 			{{svg "octicon-mute" 16 "tw-mr-2"}}
 			{{ctx.Locale.Tr "repo.issues.unsubscribe"}}
diff --git a/tests/integration/issue_subscribe_test.go b/tests/integration/issue_subscribe_test.go
new file mode 100644
index 0000000000..32001cd22d
--- /dev/null
+++ b/tests/integration/issue_subscribe_test.go
@@ -0,0 +1,44 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"net/http"
+	"net/url"
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIssueSubscribe(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, giteaURL *url.URL) {
+		session := emptyTestSession(t)
+		testIssueSubscribe(t, *session, true)
+	})
+}
+
+func testIssueSubscribe(t *testing.T, session TestSession, unavailable bool) {
+	t.Helper()
+
+	testIssue := "/user2/repo1/issues/1"
+	testPull := "/user2/repo1/pulls/2"
+	selector := ".issue-content-right .watching form"
+
+	resp := session.MakeRequest(t, NewRequest(t, "GET", path.Join(testIssue)), http.StatusOK)
+	area := NewHTMLParser(t, resp.Body).Find(selector)
+	tooltip, exists := area.Attr("data-tooltip-content")
+	assert.EqualValues(t, unavailable, exists)
+	if unavailable {
+		assert.EqualValues(t, "Sign in to subscribe to this issue.", tooltip)
+	}
+
+	resp = session.MakeRequest(t, NewRequest(t, "GET", path.Join(testPull)), http.StatusOK)
+	area = NewHTMLParser(t, resp.Body).Find(selector)
+	tooltip, exists = area.Attr("data-tooltip-content")
+	assert.EqualValues(t, unavailable, exists)
+	if unavailable {
+		assert.EqualValues(t, "Sign in to subscribe to this pull request.", tooltip)
+	}
+}