Paul Dickov’s men kept their unbeaten run going as they dispatched 10-man Charlton comfortably on home soil.
A first-half strike from Abdoulaye Meite followed by a Chris Brown penalty set Doncaster on their way as Athletic were reduced in numbers when Lawrie Wilson was sent off in the 35th minute.
A second-half thunderbolt from Mark Duffy finished off proceedings as Rovers claimed seven points from a possible nine to lift them further from the relegation zone and into 19th in the Championship.
Dickov stuck with the side which drew 1-1 with Blackpool and Doncaster attacked from the off with Gabriel Tamas seeing an effort blaze over the bar inside the first minute.
Athletic’s Johnnie Jackson followed up with a carbon copy of the Romanian full-back’s chance but his shot failed to trouble Ross Turnbull.
James Coppinger, playing with freedom and confidence, jinked his way into the box before over-running the ball after good hold-up play from Chris Brown.
Charlton’s blushes were then spared when a mistake from Jackson saw Sharp pounce but his drilled effort was well blocked by Michael Morrison.
Duffy’s in-swinging set-piece forced Alnwick into a punch away from danger before Rovers retained possession and a curling Coppinger delivery into the far post led to Charlton hurriedly clearing.
Charlton struggled to get out of their own half inside the opening 20 minutes but did have a teasing corner cleared by Doncaster’s backline.
Dickov’s men countered through Mark Duffy but Sharp’s give-and-go failed to come off as Chris Powell’s men survived.
Rovers thought they were 1-0 up in the 25th minute when a James Husband curling free-kick into the far-post saw Bongani Khumalo delicately place the ball goalwards, however, the chance somehow stayed out with Sharp unable to force home the rebound. Doncaster’s relentless pressure eventually paid off just seconds after as Meite got the final touch from point-blank range, poking in Doncaster’s opener in the 26th minute. The centre-back capitalised on Alnwick’s parry from an initial Duffy drive to fire in his first for the club.
Charlton’s misery continued as Wilson was given his marching orders for bundling over Sharp for a penalty. The offence happened when Brown left a throughball for the advancing Sharp who raced in behind the Athletic defence and as he went to strike, the visiting midfielder clattered into the on-loan striker.
The in-form Brown stepped up to coolly slot home the spot-kick past Alnwick’s despairing left-hand dive nine minutes before half time.
Further pressure from the hosts ensued as a classy touch from Richie Wellens fed in Coppinger whose low drive was well saved by Alnwick.
Rovers started in the same way they finished the first half as they pinned Charlton back. Alnwick later spilled a Duffy corner in the 50th minute but managed to get enough to see it over.
Simon Church lashed at a half-chance in a rare Charlton attack as Duffy’s grass-cutter at the other end was easily gathered.
A thunderbolt from Tamas went the wrong side of the net after the right-back was found at the far stick by Coppinger with 64 minutes gone. Rovers continued to counter and looked strong in possession.
Duffy finally made his mark in the 67th minute as he carried the ball before shifting it onto his right and unleashing an unstoppable effort for 3-0 to the hosts.
The former Scunthorpe winger could have had his brace moments later but his curling free-kick was gathered by Alnwick.
Sharp was denied a perfect homecoming as he failed to round Alnwick from a Duffy ball during the hosts’ dominance.
And David Cotterill, who came on for Sharp in the 77th minute, saw a searching effort from distance fire just over as Doncaster - who hit the bar from a Wellens strike - never looked troubled in their must-win encounter.
Goals:Meite 26, Brown pen 36, Duffy 67 (Rovers).
Rotherham: Rovers: Turnbull 7, Husband 7, Duffy 8, Brown 8 (Peterson 89), Sharp 8 (Cotterill 77), Khumalo 7, Tamas 7 (Quinn 77), Keegan 8, Wellens 7, Meite 7, Coppinger 8. Subs not used: Maxted, Furman, De Val, Stevens.
Charlton: Alnwick 6, Evina 6 (Wood 46, 6), Jackson 6, Morrison 6, Dervite 6, Stephens 6 (Ajdatevic 79), Kermorgant 6, Church 6 (Harriott 75), Cousins 6, Wilson 5, Lennon 6. Subs not used: Thurham-Vlien, Green, Sordell, Pigott.
Bookings: Stephens 75 (Charlton).
Sending-off: Wilson 35 (Charlton)
referee: Paul Tierney (Lancashire)