The 57-year-old Polish national walked out onto the wing of flight FR8164 with his hand luggage as it waited on the tarmac at Malaga airport.
He was eventually talked into getting back inside the plane by ground staff worried he was going to jump off the wing.
The man, who was later arrested by local police, had reportedly become frustrated when the plane was delayed by almost an hour leaving Stansted on New Year’s Day.
A fellow passenger on the flight, Fernando Del Valle Villalobos, told the Mail Online: "This man decided he wasn’t going to wait any longer.
"He activated the emergency door and left, saying ’I’m going via the wing.’ It was surreal."
Video footage shot by another passenger shows the man setting his hand luggage down before sitting on the wing’s edge while number of people can be heard laughing.
https://twitter.com/gorgenis/status/948468065192247296
A Ryanair spokesperson told Sky News: "This airport security breach occurred after landing in Malaga airport on 1 January.
"Malaga airport police immediately arrested the passenger in question and since this was a breach of Spanish safety and security regulation, it is being dealt with by the Spanish authorities."