Brannigan had a measured start, only 12th quickest through the first time split but he claimed the top spot in the Hot Seat as fastest with a lightning run through the rest of the course to clock 3:32.164.
His DeVinci Global teammate Smith then tore through the opening big jump section nearly two seconds faster than the Kiwi and while he lost time to Brannigan through the rest of the course, the Canadian held on to claim the victory in 3:31.764.
"I am pretty stoked," Brannigan said. "It is definite relief to be up there. This season my main aim was consistency after last year, just being in the top 20. This race I wanted to hold it open and get a really good result. It feels like a long time coming.
"My contract is up but I have no reason not to sign with DeVinci again. It is an awesome team and we all get on well."
The Hawkes Bay rider says he will ease back into riding over the New Zealand summer.
"The main focus when I get home will just be to enjoy riding, even through the summer series and after the nationals I will really step it up in training and try to come into the season really strong next year."
MacDonald has been the Kiwi standout this season with four top-10 finishes capped off with his victory at Val D'Isere.
"To tell the truth I found this week hard. I was really over it and looking forward to going home," MacDonald said. "It wasn't the weekend I wanted but I'm seventh overall and I am happy with my season."
Christchurch rider Cameron Cole (Lapierre International) also enjoyed an outstanding run to finish sixth, with MacDonald (MS Mondraker) 14th. Cole's teammate Sam Blenkinsop (Wanganui) recovered from a fall to finish 41st.
Auckland's Sophiemarie Bethell finished 16th in her first World Cup final, with Nelson's Veronique Sandler 19th.
Results, UCI Mountain Bike World Cup, Downhill, Hafjell, Norway:
Elite men: Steve Smith (CAN) 3:31.764, 1; George Brannigan (NZL, DeVinci Global) 3:32.164, 2; Greg Minnaar (RSA) 3:33.898, 3. Also New Zealanders: Cameron Cole (Lapierre International) 3:35.973, 6; Brook MacDonald (MS Mondraker) 3:37.729, 14; Sam Blenkinsop (Lapierre International) 3:44.565, 41; Reece Potter (Zerode, Takaka) 3:46.500, 49; Richard Leacock (Wellington) 3:48.597, 59;
Aaron Gwin (Trek World Racing, USA) 1260, 1; Greg Minnaar (RSA) 1162, 2; Gee Atherton (GBR) 1123, 3. Also New Zealanders: MacDonald 650, 7; Brannigan 604, 10, Cole 579 11; Blenkinsop 482, 15; Justin Leov 358, 24.
Elite Women: Rachel Atherton (GBR) 4:01.545, 1; Emmeline Ragot (FRA) 4:03.828, 2; Morgane Charre (FRA) 4: 10.398, 3. Also New Zealanders: Sophiemarie Bethell (Auckland) 4:39.378, 16; Veronique Sandler (Nelson) 4:52.828, 19.