McCarthy's strike was added to by Romelu Lukaku just after half-time for Roberto Martinez's side, who controlled the game against a Hull outfit with one eye on next week's FA Cup final.
Everton went in front after eight minutes when McCarthy finished a typically flowing move and they completely dominated, with Steven Naismith firing wide and Lukaku forcing a save just before half-time.
Chances were at a premium for the home side, who saw a Jake Livermore effort go wide and Maynor Figueroa's deflected shot saved.
But any hopes of a Hull fightback were dashed within 60 seconds of the restart as Lukaku got on the end of a fine Leon Osman ball to confidently slot home.
The result means Everton finish a hugely impressive season with their highest points tally since their title-winning season of 1986-87 and 72 points equals Tottenham's record last season of the most a team have gained without finishing in the top four.
Hull end their season 16th in the league, just improving on their previous best of 2008-09, and will head into the Wembley clash against Arsenal on the back of a five-game winless run.
Steve Bruce welcomed Sone Aluko, Paul McShane and Allan McGregor back from injury to boost his options ahead of the Cup final.
However, the goalkeeper’s first contribution of note was to pick the ball out of the net as Hull were carved open after eight minutes when Naismith slipped in McCarthy and the Irishman’s drilled effort was too hot for McGregor to keep out.
Naismith shot off-target and Livermore dragged an effort wide from 25 yards at the other end, though the game was played at a sedate pace.
Lukaku scored a hat-trick on the final day of last season and he ought to have added a second for Everton after 25 minutes when a wonderful Leighton Baines cross found the striker, but he could not get a telling touch and the ball was cleared.
Everton continued to impress and McCarthy's low cross was stabbed goalwards by Lukaku just before half-time but McGregor made a sharp low save.
But they got the second goal their play deserved within a minute of the second half when Osman's fine slide-rule pass found Lukaku who brushed aside McShane before firing home inside the area for his 16th of the season.
Substitute Liam Rosenior, Curtis Davies and Robert Koren each passed up chances to score for Hull late on, as Everton secured a first win at the KC Stadium and consigned Bruce's side to a fifth defeat in their last seven home outings.
