It's now six league wins on the trot as the Millers move up to third place in the League Two table and the visitors could be relieved they weren't on the end of a hammering.
There were three team changes in the starting line up with Marc Joseph, Pablo Mills and Derek Holmes returning but it was a quiet opening few minutes after an early home free kick had been dealt with.
Town were using the long ball and they had a shot on goal in the 12th minute after Steve Brogan had lost possession but Andy Warrington saved with ease.
Six minutes later a home free kick saw Mark Hudson head the ball back across for Chris O'Grady to find Mills who fired just wide.
That set the scene for United to do the vast majority of the attacking and O'Grady fired wide from 25 yards before Ryan Taylor's effort was also just off the target.
Graham Coughlan had a header blocked following a Joseph cross and on 29 minutes the Millers almost took the lead but O'Grady's shot hit the post with the keeper beaten.
Brogan had a chance following a good run but he fired over the bar before appeals for a handball in the Town area were rejected. In the 36th minute the visitors had another narrow escape when following a long throw in Hudson's close range effort was cleared off the line for a corner.
Then Brogan had a shot saved after another telling forward run but the breakthrough deservedly cam on 39 minutes when a long Joseph throw wasn't cleared by the Town defence and Mills' diving header was touched home by Taylor for his first senior goal.
But all the good work was almost undone in first half injury time when a rare Town attack saw Symes hit the post and Hunt's follow up effort was cleared off the line.
Five minutes into the second half, the Millers should have added a second goal when O'Grady's shot was parried out to Danny Harrison who squandered a great chance by shooting over the bar when he should have netted.
Still the home pressure continued with Taylor having a shot blocked and another effort from O'Grady was saved before a rare Shrewsbury attack on 69 minutes saw Davies have a 25 yarder saved comfortably by Warrington.
Holmes headed over the bar from a Joseph cross and on 71 minutes the Millers were again denied by the woodwork when O'Grady's superb 20 yarder rattled the bar and his follow up shot was turned round the post for a corner.
Coughlan headed wide from a corner while a rare Town look at goal saw a free kick from 20 yards wasted completely. They then won an 81st minute corner but a minute later the Millers sealed their victory when a high deep cross from Joseph was headed home at the far post by Holmes.
Still the attacking didn't stop and on 87 minutes it was almost three when Coughlan went up for a corner only for his header the hit the bar before Paul Hurst came on for his record breaking 493rd appearance.
Rotherham: Warrington, Joseph, Sharps, Coughlan, Brogan (Hurst 89), Harrison, Mills, Hudson, O'Grady, D. Holmes, Taylor. Subs: Annerson Tonge, Newsham, Ross.
Shrewsbury:Garner, Moss, Langmead, Jones, Tierney, Hall, Drummond, Hunt (Leslie 46), Ashton (Davies 61), Hibbert, Symes. Subs: Pugh, Murdock, Esson.
Referee: Carl Boyeson (East Yorkshire).
Attendance: 3,832 (295 away).
