England Under-21 forward Marvin Sordell laid on Eagles' ninth goal of the season following an error by Huddersfield captain Peter Clarke, one of several visiting players to come close to scoring during the second half.
The result means Bolton close the gap on sixth-placed Brighton to four points after bouncing back from away losses to Ipswich and Charlton, while Huddersfield remain in the bottom three on goal difference having played a game more than fourth-bottom Sheffield Wednesday.
David Ngog dragged a right-footed shot harmlessly wide from inside the area as the hosts enjoyed the better of a low-key opening.
Terriers' boss Mark Robins was forced into an early change as Jack Hunt hobbled out of the action after 15 minutes, Callum Woods filling the void at right-back, and the substitute made his presence felt in the opposition half 11 minutes later, driving forward to fire a long-range effort across Lonergan and wide from the right channel.
As the half hour approached, Ngog spurned a glorious chance to give Bolton the lead. Terriers left-back Paul Dixon lost his footing, allowing Eagles into the area unopposed, and the former Liverpool striker thrashed his subsequent cut-back wildly over from eight yards.
Huddersfield striker James Vaughan should have done better in front of goal before the interval as Oliver Norwood's miss-hit drive skidded across his path. Ward then shot narrowly wide from 20 yards to start the spell of pressure when Lonergan plunged superbly to his right to spare Knight's blushes.
Bolton's panicked defence scrambled the ball behind and, from the resulting corner, Clarke glanced against the bar.
A revitalised home team emerged for the second half and Town keeper Alex Smithies matched Lonergan's earlier heroics with a splendid stop as Ngog swivelled to send Lee Chung-yong's knockdown goalwards.
The deadlock was broken after hesitation on the ball in the right-back area was ruthlessly punished by Sordell, who burst towards goal and teed up Eagles for a clinical finish.
Huddersfield instantly returned to the front foot. Midway through the half, Scannell - earlier booked for a theatrical dive in the box - saw a shot on the angle deflect wide off Craig Dawson with Lonergan wrong-footed and Ward also had a rasping effort touched behind as Bolton's defending took on a last-ditch feel.
Ngog and Marcos Alonso had close range efforts blocked and Wanderers would have been grateful for the breathing space when Vaughan flicked a last-minute header wide with Lonergan beaten.