Big Bang Theory star steps out with his much younger girlfriend

Alaina Meyer and Johnny Galecki on the red carpet at the E! People's Choice Awards in Santa Monica, California. Photo / Getty Images

Big Bang Theory star Johnny Galecki made his relationship with his much younger girlfriend "red carpet official" yesterday.

The actor, 43, walked the red carpet at the E! People's Choice Awards with girlfriend Alaina Meyer, 21.

Galecki stepped out in a blue suit, while Meyer wore a long-sleeved black dress.

Meyer seemed to enjoy her first red carpet outing with her boyfriend, 22 years her senior, posting frequent updates to her Instagram stories through the night.

"Peeps choice was so fun with my bae," she captioned one photo.

View this post on Instagram

☠️

A post shared by Alaina Marie Avery Meyer (@alainamariemeyer) on Nov 11, 2018 at 7:43pm PST

The pair are believed to have been dating since at least July, when they started appearing on each other's respective Instagram accounts. By September, they had unveiled matching tattoos of each other's initials.

Galecki, who first found fame on Roseanne and has returned in a guest role on current spin-off The Conners, previously dated his Big Bang Theory co-star Kaley Cuoco for two years before they split in 2010.

A 2016 photo of Johnny Galecki and his ex-girlfriend, good friend and co-star, Kaley Cuoco. Photo / Getty Images

Cuoco previously said: "It was a wonderful relationship but we never spoke a word about it and never went anywhere together.

"We were so protective of ourselves and the show and didn't want anything to ruin that. But that also made it sad, too.

"That's not the kind of relationship I want — I don't want to be hiding. We couldn't do anything. It wasn't as fun as we wanted it to be," she explained.

Despite the split the actors remained on good terms, continuing with their hit show which is now in its 12th and final season.