Saracens had missed out on automatic qualification through the Premiership by just a point – they finished fifth behind Bath – and were forced to take the long route into Europe's premier competition.
But a fine performance at HQ allowed them to nail down the last English qualifying place.
They overcame Worcester last week before condemning Gloucester, who had finished 10 points behind them in the league, to a miserable end to a miserable season this afternoon.
Gloucester were aimless in attack and soft in defence as Saracens worked tries for Hugh Vyvyan and Ben Johnston to open a 17-6 lead by the interval.
Gloucester finally began to make use of all their possession after the break and moved to within a point of Saracens with tries from full-back Brad Davies and lock Adam Eustace.
But their comeback was wrecked by wayward kicking – Duncan McRae missed four from six – and Tevita Vaikona who sprinted in for the try that sealed victory eight minutes from time.
For Gloucester:Tries: Davies, EustacePens: McRae 2
For Saracens:Tries: Vyvyan, Johnston, VaikonaCon: Jackson 3Pen: Jackson