For the second time in two years, Mike Tyson said "I do" to the same woman ... in Las Vegas ... but this time, the "wedding" was MUCH more of a surprise!
TMZ has learned ... Tyson and his wife Lakiha invited hundreds of friends to a joint birthday party they threw for each other at the M Resort ... but the b-day party was merely a cover for a secret vow renewal.
After the guests arrived to the party, the couple disappeared ... only to re-emerge behind a massive curtain ... which dropped to reveal both Mike and Lahika dressed in wedding outfits.
With the crowd completely surprised, the couple proceeded to renew their vows in a traditional Muslim ceremony.
We're told the two decided to do the big "wedding" party this time around because they skipped out on a celebration when they were secretly married at a small Vegas chapel back in 2009 ... two weeks after Mike's 4-year-old daughter passed away.
Sources tell us the party was AWESOME -- guests had their choice of a steak or chicken entree ... and then they partied it up in the hotel's ballroom with a live band.