Their goal was to be in a playoff spot by Christmas.
Mission accomplished.
The victory moves the Flames to 16-12-7 for 39 points, one up on the Oilers for the second wild-card spot.
Rasmus Andersson scored the OT winner with a beautiful, bar-down blast after the Ducks rallied from a third-period deficit to force the extra period.
Michael Stone and Brett Ritchie scored for the Flames in regulation, while Jacob Markstrom made 21 saves.
The Flames out-shot the Ducks 45-23, despite playing their fourth game in six nights, and 13th, overall, so far in December.
"You know what, this has been a grind for our team," said Head Coach Darryl Sutter. "They need a break and tonight was just about digging down there a little bit, that's pretty clear. A lot of games.
"Doesn't get easier."
Indeed, but now they can enjoy three full days away from the rink and re-charge for another hectic slate, which begins with back-to-back games (vs. EDM, @ SEA) immediately after Boxing Day.
"Obviously, huge," Andersson - the OT hero - said of being back in a playoff spot. "We talked about it. 'Have a good road trip,' which we did. To come out with three out of four and seven of eight points, it's a good trip. Now we build and we keep going. We come home and we have a tough matchup right away after the break, but as I said, let's take advantage of a couple days off and enjoy some time with friends and family."
Andersson had a whale of a night, finishing with the goal, four shots and four blocks in 27:35 of ice time. He's now on a three-point game streak and has 23 (4G, 19A), overall, in 34 games this year.
The Flames were in command from the drop, and after recording the first five shots of the game and looking very much like a team on a mission, they drew first blood when Stone leaned into that patented clap-bomb to score his fourth of the season.
Trevor Lewis won the offensive-zone faceoff to the left of Ducks goalie Lukas Dostal, before Nikita Zadorov took the puck deep down the wall and made a heads-up pass back to Adam Ruzicka, who was covering at the far point. Ruzicka up the puck on a platter for Stone, and after quickly dusting it off, he wired a 95+ mph blast over the glove.
While he didn't pick up an assist, kudos to Ritchie, who set a beautiful screen in front, taking the eyes away from the Anaheim netminder.