Five days on from sealing the title with a 5-1 win over Portsmouth, Coventry received a guard of honour from Wrexham as they entered the CBS Arena pitch ahead of kick-off.
It set the tone for what was a carnival atmosphere throughout as Sky Blues supporters fully savoured the opportunity to toast their side's title success.
Despite seeing little of the ball early on, Wrexham caused the hosts problems as they looked to put a dampener on the Coventry celebrations and bolster their own play-off hopes with a positive result.
But Coventry's quality shone through in the 19th minute as Thomas-Asante volleyed Mason-Clark's curling cross into the net from close range.
It prompted chants of "1-0 to the champions" from home fans, although it was the Wrexham faithful who were celebrating just six minutes later.
Issa Kabore latched on to George Dobson's floated pass before crossing to Rathbone, who drilled through the legs of goalkeeper Carl Rushworth from 12 yards out.
Only Watford have gained more points from losing positions in the Championship than Phil Parkinson's side this season.
And the Red Dragons came agonisingly close to taking the lead before half-time, although George Thomason's right-footed strike rattled the post.
Wales international Danny Ward pulled off a crucial one-handed save to keep out Coventry top scorer Haji Wright's goal-bound header 10 minutes after the restart as the game remained finely poised.