diff --git a/plugins/chat/app/models/chat_channel.rb b/plugins/chat/app/models/chat_channel.rb
index 1a0e47d7f3e..a8e4fdfec7f 100644
--- a/plugins/chat/app/models/chat_channel.rb
+++ b/plugins/chat/app/models/chat_channel.rb
@@ -144,6 +144,6 @@ end
 #
 #  index_chat_channels_on_chatable_id                    (chatable_id)
 #  index_chat_channels_on_chatable_id_and_chatable_type  (chatable_id,chatable_type)
-#  index_chat_channels_on_slug                           (slug)
+#  index_chat_channels_on_slug                           (slug) UNIQUE
 #  index_chat_channels_on_status                         (status)
 #
diff --git a/plugins/chat/db/migrate/20221201024458_make_channel_slugs_unique_with_index.rb b/plugins/chat/db/migrate/20221201024458_make_channel_slugs_unique_with_index.rb
new file mode 100644
index 00000000000..7f1c751d8cf
--- /dev/null
+++ b/plugins/chat/db/migrate/20221201024458_make_channel_slugs_unique_with_index.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+class MakeChannelSlugsUniqueWithIndex < ActiveRecord::Migration[7.0]
+  def up
+    DB.exec("CREATE TEMPORARY TABLE tmp_chat_channel_slugs_conflicts(id int, slug text)")
+
+    channels_with_conflicting_slugs = DB.query(<<~SQL)
+      SELECT chat_channels.id, subquery.slug
+      FROM (
+        SELECT slug, count(*)
+        FROM chat_channels
+        GROUP BY slug
+        HAVING count(*) > 1
+      ) subquery
+      INNER JOIN chat_channels ON chat_channels.slug = subquery.slug
+      ORDER BY slug, created_at ASC
+    SQL
+
+    current_slug = nil
+    slugs_to_update = []
+    channels_with_conflicting_slugs.each do |channel|
+      if current_slug != channel.slug
+        current_slug = channel.slug
+
+        # Continue since we want to keep the slug for the first
+        # matching channel and just update subsequent channels.
+        next
+      end
+
+      # Deduplicate slugs with the channel IDs, we can always improve
+      # slugs later on.
+      slugs_to_update << [channel.id, "#{channel.slug}-#{channel.id}"]
+    end
+
+    values_to_insert =
+      slugs_to_update.map do |channel_pair|
+        "(#{channel_pair[0]}, '#{PG::Connection.escape_string(channel_pair[1])}')"
+      end
+
+    if values_to_insert.any?
+      DB.exec(
+        "INSERT INTO tmp_chat_channel_slugs_conflicts
+        VALUES #{values_to_insert.join(",\n")}",
+      )
+
+      DB.exec(<<~SQL)
+        UPDATE chat_channels cc
+        SET slug = tmp.slug
+        FROM tmp_chat_channel_slugs_conflicts tmp
+        WHERE cc.id = tmp.id
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end
diff --git a/plugins/chat/db/migrate/20221201035918_add_slug_unique_index_for_chat_channels.rb b/plugins/chat/db/migrate/20221201035918_add_slug_unique_index_for_chat_channels.rb
new file mode 100644
index 00000000000..1f738ef8de2
--- /dev/null
+++ b/plugins/chat/db/migrate/20221201035918_add_slug_unique_index_for_chat_channels.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class AddSlugUniqueIndexForChatChannels < ActiveRecord::Migration[7.0]
+  def change
+    remove_index :chat_channels, :slug
+    add_index :chat_channels, :slug, unique: true
+  end
+end
diff --git a/plugins/chat/db/post_migrate/20221201032830_drop_tmp_chat_slug_tables.rb b/plugins/chat/db/post_migrate/20221201032830_drop_tmp_chat_slug_tables.rb
new file mode 100644
index 00000000000..2ac238d59d9
--- /dev/null
+++ b/plugins/chat/db/post_migrate/20221201032830_drop_tmp_chat_slug_tables.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class DropTmpChatSlugTables < ActiveRecord::Migration[7.0]
+  def up
+    DB.exec("DROP TABLE IF EXISTS tmp_chat_channel_slugs")
+    DB.exec("DROP TABLE IF EXISTS tmp_chat_channel_slugs_conflicts")
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end
diff --git a/plugins/chat/spec/models/category_channel_spec.rb b/plugins/chat/spec/models/category_channel_spec.rb
index 89c950f5f7a..17d9139f6e7 100644
--- a/plugins/chat/spec/models/category_channel_spec.rb
+++ b/plugins/chat/spec/models/category_channel_spec.rb
@@ -88,9 +88,7 @@ RSpec.describe CategoryChannel do
     subject(:channel) { Fabricate(:category_channel) }
 
     context "when slug is not provided" do
-      before do
-        channel.slug = nil
-      end
+      before { channel.slug = nil }
 
       it "uses channel name when present" do
         channel.name = "Some Cool Stuff"
@@ -129,12 +127,20 @@ RSpec.describe CategoryChannel do
       end
 
       context "when there is a duplicate slug" do
-        before { Fabricate(:category_channel, slug: "awesome-channel") }
+        fab!(:awesome_channel) { Fabricate(:category_channel, slug: "awesome-channel") }
 
         it "adds a validation error" do
           channel.slug = "awesome-channel"
           channel.validate
-          expect(channel.errors.full_messages.first).to include(I18n.t("chat.category_channel.errors.is_already_in_use"))
+          expect(channel.errors.full_messages.first).to include(
+            I18n.t("chat.category_channel.errors.is_already_in_use"),
+          )
+        end
+
+        it "does not allow setting the slug conflict directly in SQL" do
+          expect {
+            DB.exec("UPDATE chat_channels SET slug = 'awesome-channel' WHERE id = #{channel.id}")
+          }.to raise_error(PG::UniqueViolation)
         end
       end
 
@@ -144,7 +150,9 @@ RSpec.describe CategoryChannel do
         it "fails if slug contains non-ascii characters" do
           channel.slug = "sem-acentuação"
           channel.validate
-          expect(channel.errors.full_messages.first).to match(/#{I18n.t("chat.category_channel.errors.slug_contains_non_ascii_chars")}/)
+          expect(channel.errors.full_messages.first).to match(
+            /#{I18n.t("chat.category_channel.errors.slug_contains_non_ascii_chars")}/,
+          )
         end
       end
     end