Walcott scored in his 350th game for the club.
Bellerin said: "Sometimes when you're getting games regularly that helps a player's confidence as well. We've been playing together in the right side for the last few weeks and it's a partnership that we both enjoy. We understand each other a lot and I think that shows on the pitch. It's great fun to play with him.
"I think you can see that he's been doing it for the past month and I'm glad to see him back to his best."