The Hatters made it 22 league games unbeaten to s
Danny Hylton was back on the scoresheet for the first time in four months to net the first just before the hour, then James Collins netted his 20th of the campaign to seal the three points in injury-time.
The win maintained the five-point advantage over second-placed Barnsley, who had won at Southend in the day's early kick-off, and seven ahead of third-placed Sunderland, who beat Plymouth at home.
Harford made one change to his starting line-up, with Elliot Lee returned to start a game for the first time since the FA Cup third round replay with Sheffield Wednesday in mind-January, with George Moncur dropping to the bench.
That meant James Shea would make his 50th appearance for the club in goal, behind a back four of Jack Stacey, Matty Pearson, captain Sonny Bradley and James Justin.
Alan McCormack anchored the midfield with Andrew Shinnie, Pelly-Ruddock Mpanzu and Lee behind a front two of Hylton and top scorer Collins.
The Hatters started on the front foot, and Rochdale picked up their first yellow card after just 31 seconds when midfielder Ethan Hamilton went into referee Lee Swabey’s notepad for a foul on Lee.
Collins, with Republic of Ireland manager Mick McCarthy in the directors’ box watching him, came close to opening the scoring in the fifth minute when Hylton, Mpanzu and Lee combined to set him up for a shot from the edge of the box, but a deflection took it just wide of Andy Lonergan’s left post.
Soon after surviving a scare at the other end when Matt Done looked to go round the onrushing Shea at the end of an incisive Rochdale move, only to lose his footing, the Hatters launched their most fluent move of the opening quarter-of-an-hour.
Justin played the ball into Collins’ feet, and the striker fed Mpanzu on the overlap down the left. The midfielder whipped a low cross perfectly into Hylton’s stride, but the Hatters’ forward was just off target with his first-time effort on the stretch.
Some determined play from Hylton, chasing a lost cause into the corner, earned a free-kick wide on the left that Justin delivered in the direction of Bradley’s head in the 27th minute. Rochdale managed to clear, but only as far as McCormack, whose volley from the edge of the box flew just over the bar.
Shea made a good save just after the half-hour, smothering at Ian Henderson’s feet as Rochdale looked to make inroads to the Hatters’ defence.
But the Town were soon on the attack again, Hylton latching onto a ball over the top and the ricochet off Jim McNulty falling back to the feet of Collins, whose right-footed shot veered wide of the far post.
Collins was next to have a go, too, as the Hatters really upped the tempo in the 39th minute, Justin playing the top scorer into the left-side of the area, but Lonergan was equal to his left-footed piledriver and Lee couldn’t dig the ball out of his feet to get a rebound shot off.
Lonergan was off his line again quickly in the 43rd minute as Mpanzu’s directness in the area took him into the six-yard box, and Shinnie raced in ahead of his midfield partner to force the ball goalwards, only for the goalkeeper to smother.
Longergan was soon picking up a yellow card for a subtleless piece of time-wasting, as referee Swabey grew tired of the visitors' delaying tactics when taking free-kicks.
And as the half flew to a close, Lee fired the Hatters' final opportunity over the bar as Collins laid the ball off beautifully into his pat 25 yards out.
We had a yellow card 31 seconds into the first half, and by the same point of the second Mpanzu had been presented with the best chance to open the scoring, when Shinnie slipped him into the Rochdale area. Lonergan, once again, was quickly out to spread himself and save well, however.
The next best chance arrived quickly, Hylton laying the ball off for Shinnie to play a fantastic through ball for Stacey to race onto from inside his own half. The right-back was clean through, but just delayed his shot long enough as he reached the penalty area for Joe Bunney to slide in and deflect wide for a corner.
The breakthrough finally came just before the hour, and it ended Hylton's goal drought that dated back to his hat-trick against Accrington at the end of October.
Stacey did wonderfully well to burst between two players on the right and get to the byline, Hylton diverting his cut-back towards goal only for Lonergan to save well again. The rebound flew to Lee, whose header came back down off the crossbar for Hylton to prod over the line ahead of Mpanzu.
In the 64th minute Hylton raced onto a McCormack ball into the corner then arced in a fantastic cross for Collins to head at goal, Lonergan saving low by his post.
Lee was keen to get in on the act, bending a right-footed 25-yarder over the bar as Collins lay prone in the penalty area, following an off-the-ball clash with Rochdale sub Jordan Williams.
Harford introduced Dan Potts for Mpanzu in the 75th minute, making the last 15 the first league minutes the midfielder has missed this season, and within two minutes the Town had fashioned another chance for Collins to add to his 19 goals, but the striker dragged his left-footed shot across the face of goal.
Henderson gave Shea something to do at the other end in the 78th minute with a tame 25 yarder that the keeper was right behind, but Lee was soon leading the charge again for the Hatters, Lonergan diving to his right to tip the ex-Barnsley man's low shot wide.
Lee was having an excellent game, but his number was up after 81 impressive minutes on his return, with Kazenga LuaLua on in his place.
Rochdale were reduced to ten men with five minutes of normal time remaining when Hamilton was shown a second yellow for a foul on Shinnie, and in injury-time Collins put the seal on the win.
LuaLua did brilliantly to keep the ball in the corner and drew a couple of defenders in, skipped past them along the byline and cut the ball back for Collins to sweep it into the top corner, left-footed, from ten yards out and equal his tally of last season - only this year is better, in his eyes, as he has all 20 in the league.
TOWN: Shea, Stacey, Pearson, Bradley (c), Justin, McCormack, Shinnie, Mpanzu (Potts 75), Lee (LuaLua 81), Hylton (Berry 89), Collins. Subs: Moncur, Cummings, Sheehan, Isted
Yellows: Mpanzu, Shinnie
Goals: Hylton 59, Collins 90+1
ROCHDALE: Lonergan, McNulty, Delaney, Dooley, MJ Williams, Camps, Done (Andrew 63), Inman, Hamilton, Bunney (J Williams 63), Henderson (Clough 71). Subs: Holden, Adshead, Wade (GK), Matheson
Yellows: Hamilton, Lonergan, MJ Williams
REFEREE: Lee Swabey