Wakefield's 21-year stay in Super League - after they returned to the top flight in 1998 with a victory over Featherstone Rovers in the inaugural Division One Grand Final - goes on after a well-deserved win over their relegation rivals.
Ryan Hampshire, who is yet to be offered an extended deal by the club, scored twice while Reece Lyne crossed in the 54th minute to put the game beyond the visitors.
Four teams were level on points heading into the final round but Trinity's win meant the Broncos were sent down.
This wasn't Trinity's first close scrape with relegation since returning to Super League.
They won their final game in 2001, 2002 and 2006 - famously consigning rivals Castleford Tigers to the drop - and beat Bradford Bulls in a tense, dramatic Million Pound Game in 2015.
Wakefield have kept themselves well clear of the relegation scrap since surviving at the Bull's expense four years ago and not many of their supporters would have expected to be nervously watching from the terraces or from behind the sofa as they fought to keep a hold of their place in the top flight.
After back-to-back top-five finishes Wakefield had the Super League play-offs in their sights at the start of 2019. However, head coach Chris Chester admitted that their plight this term has come as no real surprise.
Chester has cited the amount of players he has had to do without this year as one of the reasons for their troubles, with the likes of Tom Johnstone and Tinirau Arona both ruled out by season-ending ACL injuries.
Half-backs Danny Brough and Jacob Miller have also been out for extended periods while star forward David Fifita watched last night's action with a protective boot on his left foot.
Wakefield were also without Bill Tupou, Chris Annakin, Anthony England and James Batchelor who have all picked injuries in the last two weeks.
Trinity's injury problems proved detrimental to their top-five hopes with chief executive Michael Carter revealing that the club's medical bills have risen by 122 per cent compared to last season, a considerable drain on resources for any club.
A dreadful record in the second half of the campaign, where Wakefield won just two of 15 league games prior to last night's triumph soon saw them looking over the shoulders rather than up the ladder.
Ryan Atkins made his second debut for Wakefield after returning from a 10-year spell at Warrington Wolves at the beginning of August.
The veteran centre was just one of a number of signings who arrived late in the season to give Trinity a much-needed boost.
Morgan Escare, Adam Tangata and Chris Green also joined the club last month and all played a part last night to help Wakefield secure their Super League status.
There were plenty of nerves prior to kick off but Trinity's near-faultless first-half display soon eased the tension around the ground.
They led 8-0 at the break thanks to Danny Brough's early penalty goal and Hampshire's first try.
It came after the winger had palmed back Jacob Miller's kick to Morgan Escare. The on-loan Wigan Warriors full-back drew the defenders before popping the ball back to Hampshire who made no mistake with the finish.
London almost changed the complexion of the game on the stroke of half time but Ryan Morgan's potential try was soon chalked off after Alex Walker was penalised for a forward pass.
Every kick return, carry and tackle was enthusiastically cheered on by the home faithful, who knew how important their influence could be.
Wakefield lost their previous two meetings with the Broncos - both in the capital - earlier this year, conceding 42 points on both occasion but a return of that defensive effort never looked likely.
The lead was extended early in the second period when Hampshire took a looping pass from Miller and squeezed over in the corner.
The home fans started to believe it was going to be their night when the hosts added a third to go 18-0 ahead.
Brough dabbed a kick through the London line and Reece Lyne reacted quickest to gather and ground.
The half-back missed his first conversion of the night but added a drop-goal 12 minutes from time to leave the Broncos with a mammoth task.
Alex Walker added a late consolation for London as he got his arm out of the tackle to plant down out wide.
Hampshire was sin-binned late on for holding down before Brock Lamb added a second consolation with less than a minute to go but it mattered little as Trinity celebrated survival.
Wakefield: Escare, Jones-Bishop, Lyne, Atkins, Hampshire, Miller, Brough, Kopczak, Randell, Tangata, Kirmond, Tanginoa, Crowther. Substitutes: Wood, Green, King, Arundel.
London Broncos: Walker, Dixon, Morgan, Kear, Williams, Abdull, Lamb, Battye, Cunningham, Butler, Gee, Pitts, Yates. Substitutes: Fozard, Mason, Hindmarsh, Lovell.
Referee: Robert Hicks (RFL)