They were always in the driving seat against the struggling Spireites, although the visitors battled bravely throughout.
It needed a terrific finger-tip save from visiting keeper by Barry Roche to keep out a Chris Greenacre header in the 11th minute.
But Roche had no chance after 21 minutes when John Mullin capitalised on a defensive mix-up to fire home from close range.
The Merseysiders should have added to their lead before half-time. Gareth Taylor and Ian Goodison both headed just over and Shane Sherriff fired against a post in first-half injury time.
Chesterfield rallied a little after the break but Peter Holmes saw a shot saved.
Then the visitors wasted a terrific chance to level in the 54th minute. Colin Larkin latched on to a woeful back pass by substitute Jason McAteer but his shot cannoned back off a post.
Tranmere settled it after 73 minutes when Greenacre tapped home his 14th league goal of the season from close range from a cross by Chris Shuker.
Paul McLaren was excellent in the Rovers midfield and Greenacre was always busy upfront. Holmes and Mark Allott tried hard for Chesterfield.
Substitute Jamie Jackson also did his best in the closing stages but a tenth away reverse left the Spireites struggling near the relegation zone.