Tonight's episode began with a first for the show, with all seven finalists racing each other on the Snow Cross.
The 175 metre-long course was made harder for the final, with bosses adding two kickers.
Trainer Graham Bell predicted the contestants would "gang up on Louis", the bookies' favourite to win, but the Olympian proved too quick for them, zooming straight out the starting gate.
Louis maintained his early lead and finished first, with Jason Robinson and Spencer Matthews coming second and third respectively.
Kadeena Cox looked set for fourth place, but she stumbled at the second kicker, allowing Lydia Bright - who was eliminated last week, but returned as a replacement for Gareth Thomas - to overtake her.
Losers Kadeena, Amy Willerton and Emma Parker Bowles then faced the first ski jump of the night, hoping to progress to the next stage of the final.
The Jump 2017 week six - first ski jump result
- Amy Willerton - 16.08 metres
- Emma Parker Bowles - 14.10 metres
- Kadeena Cox - 15.38 metres
As she jumped the shortest distance, Emma was eliminated.
Event two was the Ultimate Ski Cross, described by presenter Davina McCall as the "toughest course we've ever built".
The remaining contenders were split in to groups of three for two separate races, with the loser of each being eliminated immediately.
Louis won the first race without contest after Lydia suffered an early crash, taking Jason down with her.
Jason was able to reattach his ski and completed the course as runner-up - but Lydia had no such luck and was eliminated without finishing.
The second race saw Spencer win, with Kadeena initially in second. However, Amy narrowly managed to overtake her at the final hurdle, putting Kadeena out of the running.
Having made the final four, Louis, Jason, Spencer and Amy's last challenge was to face the ski jump one more time - and this time, whoever jumped furthest would win.
The Jump 2017 - final ski jump result
- Jason Robinson - 16.35 metres
- Louis Smith - 18.05 metres
- Amy Willerton - 15.18 metres (DQ)
- Spencer Matthews - 18.98 metres
Although Amy scored 15.18 metres, she failed to land her jump properly and fell before the crash line, meaning her attempt was disqualified.
The six-week series came down to a battle between Louis and Spencer. In a surprise result, the former Made In Chelsea star was crowned champion, taking home the cowbell trophy.
He managed a huge 18.98 metre distance, setting a new record for The Jump's largest ski jump score. It was previously held by Sid Owen, who managed 18.85 metres in last year's series.
Reacting to his victory amid a firework display, Spencer said: "Amazing! I'm so happy!"
Channel 4 has yet to confirm whether The Jump will return for a fifth run.