Doncaster kept themselves in the mix for automatic promotion against Scunthorpe, who are now two points from safety in League One.
Christian Ribeiro chested David Cotterill's cross into his own net under pressure from Martin Woods.
And the hosts took full control after the break when Cotterill followed up on Iain Hume's parried effort.
Rob Jones made it 3-0 with a towering header and Billy Paynter added a fourth from 20 yards out soon afterwards.
VIEWS FROM THE DRESSING ROOM
Doncaster Rovers manager Dean Saunders told BBC Radio Sheffield:
"We could have scored 10 today. I started the team a week before the season started... I spent time making sure that we're organised and we're defensively sound.
"I said last week there's more to come from the team and today they showed it.
"They played really well and we could have scored more goals."
Scunthorpe United manager Brian Laws told BBC Radio Humberside:
"What I saw in the second half - I've got more passion on the touchline than the type of players we have at this football club.
"They haven't got the passion and the desire to move forward.
"What they are is a team that want to play nice football on a nice summers day.
"It doesn't work like that - it's hard work, it graft, it's pride, it's passion and they didn't show that in the second half."