The Frenchman, a £400,000 transfer window signing from Charlton, opened his account for the club by firing through the legs of Rovers goalkeeper Sam Johnston midway through the first half.
Kermorgant’s powerful header doubled Cherries’ lead on the stroke of half-time before Harry Arter bagged the first of his two goals to make it 3-0 just after the break.
Striker Kermorgant completed his treble with a diving header from a Simon Francis cross before Arter rounded off the scoring eight minutes from time.
Kermorgant was handed his first start as boss Howe made two changes to the Cherries starting line-up with Ryan Fraser, who had been laid low with a bout of bronchitis recently, earning a recall.
Fraser created the first chance for Kermorgant after just three minutes but the frontman headed the Scotsman’s cross straight at Rovers goalkeeper Sam Johnstone.
Dean Furman blazed a presentable opportunity wide of the target for Rovers before Fraser’s stinging drive, following a neat one-two with Lewis Grabban, was pushed past the post by Johnstone.
Bongani Khumalo’s last-ditch saving tackle prevented the lively Fraser from taking aim and Cherries went close to breaking the deadlock from the resultant corner.
But after Andrew Surman had met Harry Arter’s delivery with a fierce drive, Rovers goalkeeper Johnstone was well placed to palm his effort over the crossbar.
Kermorgant fired wide following another well-worked corner, the striker latching on to Harte’s flag kick after Arter had foxed the Rovers defence with a clever step-over.
And as Cherries continued to create chances, Matt Ritchie’s deflected shot whistled past the upright after Kermorgant’s header had teed him up.
Cherries were finally rewarded for their litany of goalscoring chances when they made the breakthrough after 26 minutes.
Kermorgant gave his marker the slip and slotted the ball between the legs of Rovers goalkeeper Johnstone after meeting a cross from the left from Harte.
And just seconds later, Cherries were denied a penalty when referee Darren Sheldrake turned down their appeals after Surman had been sent sprawling by Abdoulaye Meite.
Fraser, slipped in by Kermorgant’s defence-splitting pass, saw his shot turned past the post by the overworked Johnstone before Cherries doubled their lead on the stroke of half-time.
Kermorgant outjumped his marker at the far post and powered home a header after Simon Francis had picked him out with a deep cross from the right.
Grabban went close to adding a third when he held off Khumalo and let fly with an angled drive, only for Johnstone to beat away the striker’s fierce drive.
Arter made no mistake when he extended Cherries’ lead five minutes into the second half, the midfielder’s venomous strike from the edge of the box fizzing past Johnstone.
And Kermorgant completed his hat-trick with a header from a Francis cross after 73 minutes, the Frenchman diving full length to plant the ball past Johnstone.
Sarcastic cheers from the travelling supporters greeted an effort from Rovers substitute Theo Robinson as the visitors mustered their first shot on target after 75 minutes.
Arter made it 5-0 when he swept home the loose ball after Johnstone’s weak punch had fallen invitingly for him following another Harte corner in the 82nd minute.
Substitute Tokelo Rantie had a couple of late chances to add to Rovers’ misery, the South Africa international seeing a left-foot shot go wide before lifting another opportunity over the crossbar.
Cherries: Camp, Francis, Cook, Elphick, Harte, Ritchie, Arter, Surman, Fraser (Pugh, 75), Kermorgant (Rantie, 75), Grabban (Coulibaly, 83).
Unused subs: Smith, Pitman, O’Kane, Allsop (g/k).
Rovers: Johnstone, Tamas, Khumalo, Meite, Husband, Keegan, Wellens, Furman (Cotterill, h-t), Brown, Bowery (Robinson, h-t), Coppinger.
Unused subs: McCullough, De Val, Peterson, Stevens, Maxted (g/k).
Booked: Keegan, Tamas, Khumalo.
Referee: Darren Sheldrake (Surrey).
Attendance: 8,983 (including 398 away supporters).