John Cena is a MARRIED MAN -- tying the knot with his girlfriend Shay Shariatzadeh in Tampa, Florida ... official records show.

The couple began dating back in early 2019, following Cena's high profile split with ex-fiancee Nikki Bella in 2018.

Cena and Shariatzadeh got very serious very quickly -- and were spotted making out all over town for the past year!

Apparently, the two got engaged on the down-low -- and filed for a marriage certificate in Florida in early October.

And, according to official documents obtained by TMZ Sports, they swapped "I Dos" on Oct. 12 in a ceremony in Tampa.  News of the marriage was first reported by PWInsider.

BTW ... Shay was born in Iran but is a Canadian citizen. She works as a product manager for a tech company in Vancouver.

Cena is a pretty famous wrestler, actor, rapper and male g-string enthusiast (seriously!).

We reached out to Cena's camp for comment -- but you know, he's probably off doing newlywed things.

Mazel tov!