The one-point victory ensured Exeter will play Heineken Cup rugby again next season, along with Gloucester, with Bath's loss to Saracens made irrelevant.
It also marked the last game in respective club colours for two long-serving players.
Exeter's number eight Richie Baxter made his final appearance for the club, his 431st in a Chiefs' shirt, since he made his senior debut away to Fylde 16 years ago.
Gloucester flanker Peter Buxton, meanwhile, signed off with his 274th appearance for the Cherry and Whites before making the short trip down the M5 to play Championship rugby under Andy Robinson at Bristol.
Exeter started full of confidence running the ball from deep and they scored the opening try after six minutes as scrum half Hayden Thomas fed his half back partner Steenson.
The fly-half passed the ball to inside centre Jason Shoemark who wiggled at the tackle enough to offload of lock Dean Mumm who scored, with Steenson adding the touchline conversion followed by a 40 metre penalty.
Exeter continued to dominate possession and again pressed the Gloucester line with a break from Mumm, who fed lock Damian Welch. The second-row was tackled but rolled towards the line to touchdown.
Referee Greg Garner referred the decision to the television match official Geoff Warren who, after a long deliberation, awarded the try. Steenson was off target with the conversion from out wide but then added a 20 metre penalty.
Gloucester finally got point on the board after 20 minutes through a penalty from fly-half Freddie Burns, followed by their first try when Jonny May burst 45 metres down the touchline.
With 10 minutes of the first half remaining, another Exeter error led to Burns breaking from his own half and, with a man over, fed lock Lua Lokotui who shipped the ball to winger Charlie Sharples, who fired his afterburners to score Gloucester's second try, with Burns adding the extras.
Henry Trinder added the Cherry and White's third with an interception try after a mistake from Scaysbrook.
The centre raced away avoided a couple of half tackles to score under the posts. Burns conversion put the visitors in front for the first time.
But Exeter regained the lead on the stroke of half time after a series of infringements at a string of 10-metre scrums saw referee Garner award a penalty try. Steenson's conversion gave the Chiefs a 25-22 lead at the break.
The Exeter fly-half increased the Chiefs lead with three penalties in the opening 15 minutes of the second period.
Gloucester woke up midway through the half with full-back Rob Cook crossing in the corner for the bonus point try.
Burns added the conversion and a 30 metre penalty to reduce the arrears to two points with 17 minutes remaining, but, with the wind having turned in his favour, Steenson added his sixth penalty.
With under eight minutes to go, Burns squeezed in the corner for Gloucester's fifth try before adding the conversion with the ball bouncing off the far upright to get the Cherry and Whites back in to the lead.
Steenson was then short with his touchline penalty attempt with less than three minutes on the clock before full-back Luke Arscott sliced a drop goal.
However, Steenson redeemed himself from the penalty tee to step up and kick the points which sealed victory and European rugby for next season.
- Sports & Recreation