But it wasn't just about Ellen. The daytime talk show host also had a big birthday gift for her audience. Watch all of the surprises unfold below.
The actress appeared at the tail-end of the video mashup of Hollywood's biggest stars wishing Ellen a happy birthday.
"Hi Sweetheart, happy happy happy birthday," Aniston said at the end of the video. "I'm so sorry I couldn't be there tonight, today, but you know, I'm shooting and uh, I just want to wish you the happiest birthday, we'll celebrate for more to..."
Cue DeGeneres' stage doors opening to reveal Aniston.
"I was trying to do a bit and then they opened the doors and I was going to run out and do a whole dance up and down the stairs," Aniston said.
But nonetheless, DeGeneres was still surprised by her appearance and reminisced on the "Friends" star bringing a welcome mat to her show 15 years earlier when she was one of her first few guests. In turn, Aniston remembered the first time they met at DeGeneres' 38th birthday party.
"I remember being absolutely in awe of you," Aniston said. "I idolized you."
Hart surprised DeGeneres with an oversized piece of renaissance art with a cut out hole for his face, and refused to allow Ellen to leave it behind.
"You know why I got you this," the comedian said. "Well, every time I come on here, you always say, 'Oh my God, Kevin. You're so funny.' You're like, 'Oh my God, Kevin.' You always say God and my name so now you've got this to look at every day. I'm your God."
Hart also tried to give Ellen $60 to mark her $60 birthday, but since he only had a Benjamin Franklin he took gift number two back.
Ellen decided to spread her birthday love by gifting her audience $1 million through her partnership with Cheerios. Yes, you read that right. $1 million, but it was split between the audience collectively. So with about 400 people in the studio, each person walked away with $2,500.
The surprise was part of her "One Million Acts of Good" campaign.
"Thanks to every single person in this audience, it is filled with goodness and we have reached one million acts of good because of all of you. So, I wanna do something that we've never done before," Ellen said. "Hold onto your Cheerios because all of you are splitting one million dollars! That's a lot of money!"