But, although the Crusaders took a 15-3 lead into the break and led 22-3 straight after halftime thanks to Kieran Read's converted try, the Lions never gave up. Malcolm Marx's converted try with 15 minutes left brought the big crowd back into the contest and turned the momentum back the home side's way.
Corne Fourie's try under the posts narrowed the gap to eight points and made for an excruciating final few minutes for the Crusaders, but a lineout steal by Sam Whitelock - reminiscent of his intervention in the World Cup semifinal against the Springboks - gave the visitors some comfort and then replacement halfback Faf de Klerk dropped the ball cold at a ruck and that was effectively that.
It was a courageous second-half effort from the Lions, who fought back superbly to win their semifinal against the Hurricanes. Had they beaten the Crusaders despite their numerical disadvantage it would have been one of the biggest comebacks in Super Rugby history, but Scott Robertson's men were not to be denied.
For Robertson, in his first year at charge at this level, this was a personal triumph. At the fulltime whistle he raised his fist and celebrated before running on to the field and hug his players, all of whom looked emotional.
They did it the hard way despite losing only one match all season and their eighth title is richly deserved. They are only the second team to win a title abroad, and the first since the Crusaders team of 2000, who did it in Canberra.
They roared out to a brilliant start with Seta Tamanivalu running in a try from 75m and Jack Goodhue scoring in the left corner - all within the space of 12 minutes. Both tries came from turnovers and the Crusaders had the edge at the breakdown despite not committing players there.
They were accurate - more so than the Lions, and once Smith went off, and they won a penalty from a scrum kicked seconds after the halftime siren, it looked as if it would be one-way traffic.
But despite Read's try after halftime, the Crusaders couldn't capitalise further and had to rely on their defence - brilliant all season - to win it.
Midfielder Ryan Crotty was brilliant for the Crusaders and is set to play a big part for the All Blacks in the Rugby Championship, with Read and Whitelock excellent too.
Robertson went to his bench early - and Mike Alaalatoa, Luke Romano and Wyatt Crockett all made important impacts.
It was a massive collective effort from Robertson's history makers. They deserve their success and the plaudits of their supporters, many of whom will no doubt flock to Christchurch airport to welcome them arrive home.
Skipper Whitelock said afterwards: "It's amazing, the whole group has been working hard all year and it's not just the boys here, it's the guys at home, the supporters, our families, it's been a massive 11 or 12 months. I'm just so proud of the boys tonight. They fronted, especially today.
"No one had us picked from the word go. We just believed in ourselves. We started the season really well, the energy the whole team brought was amazing."
Asked whether he thought his side had it won at halftime, Whitelock said: "We knew we had to play. The Lions are a great side, they showed it all year. They score a massive amount of points in the last 20 minutes - we knew we had to keep playing, keep attacking. Full credit to them, they put us under a massive amount of pressure. I'd hate to know how many tackles we made but the boys showed the grit that I know they have."
Crusaders 25 (Seta Tamanivalu, Jack Goodhue, Kieran Read tries; Richie Mo'unga 2 cons, 2 pens)
Lions 17 (Malcolm Marx, Corne Fourie tries; Elton Jantjies 2 cons, pen)
Halftime: 15-3
