The 59-year-old actor gave the loved-up duo a day to remember by turning up to their nuptials unexpectedly in Georgia to wish them well after meeting them the day before at a bar.
The 'Grease' star - who donated his former plane to a GA museum last week - was in the state renewing his pilot's license when he bumped into the young couple and learnt that they were tying the knot the next day.
John was "down to earth about the whole ordeal" and came to the occasion dressed in a T-shirt and a baseball cap from the night before and happily posed for photographs with the whole bridal party.
A friend of the groom shared the photographs on Reddit along with the caption: "My friend ran into John Travolta the night before his wedding, and he shows up the next day."
The 'Savages' actor pulled a similar wedding stunt in 1977 - when he was less well known - with Robin Williams.
John recalled the wedding antics in an interview a few years ago, saying: "We were having fun, starting to relax [at a restaurant in Santa Barbara, California], when we saw there was a wedding next door. We figured we'd crash it."
Robin then added: "They figured out who we were. Some guy yelled out, 'Hey, they really are Mork and Vinnie Barbarino!'