Saints went clear in second place in Super League, with Ade Gardner's four tries setting the pace against opponents whose indiscipline reduced them to 11 players at one stage.
Rovers won at Knowsley Road last season, but never remotely looked like doing repeating that feat once Saints assumed total control midway through the first half. Rovers, beaten 54-0 by Saints at Murrayfield three weeks ago, picked a side heavily slanted toward size and strength. Not that it did them a great deal of good early on, with Gardner powering his way through the tackle to open the scoring after three minutes.
The Robins' reply was a clever kick from Michael Dobson, which sat up perfectly for Kris Welham to claim a try which Dobson converted. That ushered in a passage of play during which Saints made a series of mistakes reminiscent of their trials and tribulations at Salford a week ago. Rovers, however, turned down the invitations to extend their lead.
Predictably, they paid the price when Saints hit them with three tries in 10 minutes. Gardner scored his second in similar manner to his first, Tony Puletua went over from a pass from Chris Flannery, who then scored himself from Keiron Cunningham's lofted ball.
The pressure continued and Rovers' increasingly desperate tackling led to both Ben Cockayne and Ben Fisher being sent to the sin-bin for offences in the tackle.
A full complement of 13 could not hold Saints, so 11 were hardly likely to do so and Jake Emmitt got over for Saints' fifth try just before the interval.
Puletua was too strong for Rovers' defenders again in setting up Scott Moore for the first try of the second half, before Gardner welcomed Cockayne back by going over the top of him once more to complete his hat-trick.
Kyle Eastmond chipped in with a sparkling solo effort to go with his five conversions, before another crafty Dobson kick created a second Rovers' try for Clint Newton. The game had long since gone away from the visitors, however, as Eastmond emphasised by releasing Matt Gidley for the simplest of tries and then kicking to the vacant wing to give Gardner his fourth.
Jonny Lomax's try and goal followed by James Roby and Andrew Dixon's efforts took Saints well beyond their tally in Edinburgh at the start of May. At least Rovers do not have to play them again this month.
The Rovers coach, Justin Morgan, refused to comment on the refereeing of James Child, who apart from the two men sent to the sin-bin, punished them heavily in the penalty count. "I don't think the scoreline reflects the effort we put in but being down to 11 men took a lot of the juice out of us," he said.
St Helens Lomax; Gardner, Gidley, Flannery, Foster; Pryce, Eastmond; Graham, Cunningham, Hargreaves, Clough, Dixon, Roby. Substitutes used Puletua, Moore, Ashurst, Emmitt.
Hull KR Briscoe; Fox, Clinton, Welham, Cockayne; Murrell, Dobson; Vella, Hodgson, Clinton, Netherton, Galea, Watts. Substitutes used Lovegrove, Wheeldon, Cook, Fisher.
Referee J Child (Batley).