After scoring a power-play goal on a deflection at 16:03 of the second period to make it 3-1, Monahan put the game away in the third, making it 5-1 at 6:43, taking a drop pass from Johnny Gaudreau and neatly beating goaltender Spencer Knight on a move from in-close.
Rasmus Andersson, with his first of the season, Matthew Tkachuk and Blake Coleman also scored for Calgary (18-11-6), which snapped a four-game losing streak and won on home ice for the first time since Nov. 29.
The Flames entered the night 2-7-1 in their previous 10 games.
Sam Bennett scored the lone goal for Florida (26-8-5), which had its four-game winning streak and nine-game points-streak (8-0-1) snapped.
The next outing for both teams will be in Edmonton with the Panthers’ second stop on a five-game road trip taking place on Thursday. Calgary isn’t back in action until Saturday when the Flames play the Oilers at Rogers Place.
Markstrom, who has given up four or more goals in four of his previous five starts, made 28 stops to improve to 13-8-5.
After starting the last seven games, Sergei Bobrovsky got the night off with Knight getting his first start since Dec. 30. Knight made 26 saves. His record falls to 7-5-2.
Calgary got off to a fast start, getting a power play four minutes into the game and taking just 23 seconds to take advantage with Andersson knocking in his own rebound from the slot.
The Flames extended their lead to 2-0 at 11:36 of the first. A stretch of prolonged pressure by Calgary’s newly formed second line culminated in Coleman’s seventh goal, the assists going to his linemates Andrew Mangiapane and Mikael Backlund.
But Bennett, in his first game back in Calgary scored 12:36 into the second to cut Florida’s deficit in half. Bennett was traded to Florida ahead of the trade deadline last season after logging 402 games with Calgary over six seasons. He’s been a revelation since joining the Panthers scoring 22 goals in 40 games.
The power play was key for the Flames striking twice on three opportunities after entering the game 0-for-10 during the losing streak.
Gaudreau had his first four-assist game ever on home ice and just the second of his career. Tkachuk also kept his offensive hot streak going with three points. He has 13 points (six goals, seven assists) over his last eight games.
Although the Panthers own the league’s best home record at 21-3-0, they haven’t enjoyed the same success away from FLA Live Arena, now 5-5-5.
For the Flames, they have struggled similarly at the Saddledome, picking up their first win since Nov. 29. They’re 5-4-4 on the year.
Notes: Gaudreau’s only other four-assist game was in Nashville on Feb. 21, 2017… It was the first time this season Florida did not get a point from a defenceman… Mason Marchment returned to the Panthers lineup for the first time since Jan. 1. An assist gives him a five-game point streak.