Emery improved to 12-0 in getting his 12th career shutout, and first since Feb. 1, 2010, when he blanked the Flames while with Philadelphia.
Emery was tested several times, but the Blackhawks outshot the Flames 35-16 in sending them to their 10th straight road loss (0-9-1).
``Our defense was really on,'' Emery said. ``We continued to apply pressure, but really didn't give much up. It was a great night defensively.
``It's always good to put a zero on the board, but I'm just glad to get a win.''
In their two previous games - losses to Anaheim and Los Angeles - the Blackhawks got sloppy late and blew third-period leads.
But after getting a two-goal lead late in the second period Tuesday, the Blackhawks managed the puck and their defensive coverage effectively, and finished the job.
Emery went 58 games between shutouts, a period that was punctuated with him undergoing career-threatening hip surgery.
But Emery, who said he didn't even remember his last shutout, has been perfect for Chicago this season as a backup to Corey Crawford.
``It's a good team. It's a different situation. I just take it one shot at a time,'' he said.
Calgary hasn't won in the United Center in five years, going 0-8-1 in Chicago since beating the Blackhawks 4-2 on March 16, 2008.
Leddy and Seabrook's goals both deflected off Calgary goalie Miikka Kiprusoff, who stopped 33 shots.
Patrick Kane assisted on both scores, and has five goals and nine assists in a seven-game point streak.
With the win, Chicago improved to 25-4-3 and remained in first place overall in the NHL with 53 points.
The Blackhawks ended their second two-game losing streak of the season following an NHL-record start of 24 games without a regulation loss.
``We had a couple slipups in the last couple games, but if you looked at the games before, 12,13,14 (of them) were one-goal games and we won,'' Kane said. ``One of the things we've been trying to do all year is to try to get better as a team.
``Even when we were on that long winning streak and it seems everything was golden in here, there were still some problems that we needed to fix.''
The Flames' 16 shots were a season low, one fewer than the 17 they took in a 3-2 win at home over St. Louis on Sunday.
``We didn't create nearly enough, although we had some spurts in the first,'' Calgary captain Jarome Iginla said. ``In the last 10 minutes in the first we had something going, but in the second they took over.
``We haven't created enough on the road. And we got outcompeted tonight - all of us - except Kip, who was great again in net for us.''
Leddy scored the only goal of the first period at 7:09, beating Kiprusoff with a shot that hit his left pad and then bounded in between his legs.
Leddy's chance resulted from a broken play. Kane had tried to center from the right corner to Dave Bolland in the slot, but Calgary's Curtis Glencross accidentally deflected the puck to Leddy, who had pinched down to the left circle.
Although Chicago dominated early, the Flames kept the Blackhawks pinned in their zone at times late in the first.
Emery had to be sharp a couple of times, including on a close-in chance by Iginla with 1:39 left.
Emery made a quick, point-blank pad save on Lee Stempniak 2:50 into the second following a Chicago turnover in the high slot to keep the Blackhawks ahead.
Chicago failed to cash in on a four-minute power play early in the second after Calgary's Jiri Hudler was given a double-minor for high-sticking Bolland in the face.
The Blackhawks outshot Calgary 16-3 in the second, and Seabrook made it 2-0 with 2:12 left in the period.
Seabrook's shot from the right circle ticked off Iginla's stick, then fluttered in off Kiprusoff's glove as he reached awkwardly in an attempt to grab the puck.
Kiprusoff made a sprawling save on Andrew Shaw 3:15 into the third to keep it close, then added several point-blank stops late in the period.
Emery stopped Stempniak again from the doorstep in the final minute to preserve the shutout.
Notes: Before the game, Chicago coach Joel Quenneville said both Hossa and Sharp ``are progressing,'' and Hossa skated on Tuesday. However, it's doubtful whether either will be able to play on Friday when the Blackhawks host Anaheim in a meeting of the top two teams in the Western Conference. ... The previous time the Flames and Blackhawks met, on Feb. 2 in Calgary, Emery made a career-high 45 saves to pace Chicago to a 3-2 shootout win. In that game, Calgary outshot Chicago 47-19. ... Calgary D Cory Sarich played in his 900th NHL game.