It was a thrilling match-up between the NHL's top home team and top road team, producing a wild back-and-forth game with multiple lead changes.
Tied 4-4, Iginla put the Flames back into the lead for good just 34 seconds into the third period.
Looking more like a "Hail Mary" pass in football, Craig Conroy flipped the puck high in the air and into the San Jose zone. Alex Tanguay outraced Sharks defenceman Douglas Murray to the loose puck, stopped, and then fed a perfect pass to Iginla trailing in the slot who then one-timed his 30th of the season past Evgeni Nabokov.
The goal was Iginla's 315th of his career moving him past Joe Nieuwendyk into second spot on the Flames all-time list. The leader is Theoren Fleury (364).
Daymond Langkow added his second of the game at 16:55 and Marcus Nilson wrapped up the scoring with an empty net goal.
Dion Phaneuf and Matthew Lombardi also scored for Calgary (32-21-9). The Flames improve to 25-6-1 at the Pengrowth Saddledome including a 11-1-1 mark in its last 13.
The win moves the Flames into a tie with Minnesota for second spot in the Northwest Division, three points back of Vancouver.
Matt Carle, Joe Pavelski, Mike Grier, and Kyle McLaren scored for San Jose (38-23-1). The Sharks finish up a stretch of eight straight road games with a 4-4 record.
Calgary led 2-0 after 20 minutes but that lead evaporated in a wild second period in which the Flames surrendered four goals in a period for the first time all season.
Carle got the Sharks going with a power-play goal at 4:36.
Sixty-six seconds later, the game was suddenly tied 2-2 as Grier slid a backhand pass to the front of the net that was jammed in by Pavelski.
San Jose took its first lead of the night at 15:11 when Phaneuf mishandled the puck at the Sharks blue-line and Grier raced away on a breakaway scoring his third shorthanded goal with a nifty deke to his backhand.
The Flames, however, took just eight seconds to answer back.
Off the ensuing face-off, Langkow whacked the puck forward into the Sharks corner. Rookie defenceman Marc-Edouard Vlasic's clearing attempt up the boards was kept in by Roman Hamrlik, whose shot was deflected by Iginla in front.
San Jose took its second lead of the period at 18:56 when McLaren gloved down Hamrlik's clearing attempt and ripped a slapshot past Miikka Kiprusoff.
Again, Calgary answered right back - this time waiting just 31 seconds. Iginla's pass sent away Lombardi blazing down the wing and he whipped a shot inside the far post.
Just over two minutes after Phaneuf had opened the scoring, Langkow put the Flames up 2-0 neatly tucking the puck inside the goal post after Nabokov couldn't control a rebound from Lombardi's wrist shot.
Phaneuf gave Calgary a 1-0 at 5:26 of the first period when the Flames red-hot power-play converted its first man advantage of the night.
From the side boards, Kristian Huselius threaded a pass across the ice to Dion Phaneuf breaking in on the other side and the Flames defenceman snapped a shot into the top corner for his 16th goal of the season and team-leading 12th on the power play.
Calgary finished 2-for-4 with the extra man.
Ranked 24th in the NHL on the power play on Feb. 2, Calgary has gone 19-for-62 in the dozen games since, a 30.6 per cent efficiency that has moved Calgary into the top 10.
San Jose's top ranked power play went 1-for-7.
Notes: - Iginla's first goal was his 100th career power-play goal... Langkow's two goals gives him 62 points on the season, tying his career high set in 2001-02 with Phoenix... Conroy (elbow) returned to action after missing one game... Rookie Calgary RW David Moss (facial lacerations) missed his third game but is expected back as soon as Monday... San Jose C Patrick Marleau played in his 700th career game. He is the Sharks all-time leader in games played... With Vesa Toskala placed on injured reserve, Nolan Schaefer was recalled from Hershey Friday and backed up Nabokov.