Four second-half tries, from full-back Nick Abendanon, replacements Matt Gilbert and Semesa Rokoduguni plus New Zealander Stephen Donald, added to a first-half touchdown from Olly Woodburn. Centre Sam Vesty added a penalty and two conversions.
Gloucester hooker Huia Edmonds scored his side's only try of the game.
Danny Cipriani came back to haunt his old club, scoring one of Sale's five tries as they booked a place in the semi-finals with a 33-30 victory at Wasps.
Cipriani missed the Premiership fixture at Adams Park in December after being dropped but produced a strong second-half showing in a match that turned on Will Taylor's sin-binning.
In his absence, the Sharks ran in three tries and managed to hold off a late onslaught to ensure Leicester can no longer catch them, regardless of their result at the Scarlets on Sunday.
Kearnan Myall, Sam Tuitupou, Tommy Taylor also crossed for the Sharks, who were awarded a first-half penalty try, while Charlie Hayter and Charlie Davies touched down for Wasps.
An under-strength Saracens qualified for the semi-finals with a hard-fought 22-12 victory over Worcester at Sixways.
Saracens pipped London Irish to top Pool Three and probably face an away semi-final when the competition resumes in the middle of March.
They scored an excellent early try through the outstanding Ernst Joubert, but had to rely on the goal-kicking skills of scrum-half Ben Spencer for the remainder of their points.
Worcester were disappointing as, on paper, this is a game they should have won, but they were out-battled by a determined Saracens. The defeat ensured they finished bottom of Pool Two.
Exeter ended a run of six games without a win in all competitions as they went top of Pool One with a 28-19 triumph and denied Northampton progress to the knockout stages of the competition.
The Chiefs will have to wait for the result of Sunday's game at the Brewery Field to see if they are pipped to a semi-final place by Harlequins, who only need a point from their game against Ospreys.
Exeter dominated the scoring in the first half and led 22-5 at the break after tries from Ben White, Jack Nowell and a first touchdown from Watisoni Votu, with Ignacio Mieres adding two conversions and a penalty to an Alex Waller try.
Northampton looked a refreshed side at the start of the second half and they reduced the arrears with two tries from Lee Dickson, both converted by Stephen Myler, with Mieres replying with two penalties.
