Simpson-Daniel grabbed a try in either half for the home side
Gloucester produced a clinical display to dominate an entertaining West Country derby with Bath.
Nicky Robinson capped a fine league debut with a late breakaway try to end any hope of a late Bath fightback.
James Simpson-Daniel finished off a good first-half move to score their opening try and then ran 75m to finish off a fine interception.
Shontayne Hape's late try brought Bath within two scores of their rivals, but Robinson sealed his side's opening win.
Bath's cause was not helped by some hapless goalkicking, with Ryan Davis, who took on the kicking duties in the absence of Butch James and Olly Barkley, setting the tone for an error-strewn display with two early penalty misses.
In contrast Robinson hardly put a foot wrong as he opened the scoring with a 10th-minute penalty.
The Wales fly-half was at the heart of their best play and found space for Eliota Fuimaono-Sapolu to send Simpson-Daniel over for their opening try, which Robinson duly converted.
They went into half-time 10-0 up but it should have been more convincing, with Tom Voyce blowing their best chance of adding to the scoreline when he knocked on with team-mate Charlie Sharples unmarked outside him.
Gloucester lost flanker Andy Hazell to the sin-bin for stamping on the calf of Bath flanker Julian Salvi before Mike Tindall limped off early in the second half.
But the visitors failed to capitalise and Simpson-Daniel gathered Bath skipper Michael Classens's loose pass before running almost the length of the field to score, with Robinson adding the extra points.
Hape finished off Bath's best move of the match to at least put some points on the board, although there were suggestions of a forward pass from Danny Grewcock in the build-up.
But the last word went to Gloucester and Robinson, who picked off another questionable pass - this time from Tom Cheeseman - to score a try he comfortably converted.
Gloucester head coach Bryan Redpath: "Nicky [Robinson] has got a reputation for being a calm and tactically aware player. He has been unlucky with Wales.
Redpath praises players' hard graft
"I thought he controlled the game well. On a percentage basis, I thought he was outstanding.
"The players understand where it went wrong last season. They have put some of last season's nightmare to bed. All I can ask is they put themselves on the line, rather than hide behind an excuse."
Bath head coach Steve Meehan: "It didn't feel too good. We lacked discipline, not just from giving away penalties and free-kicks but looking after the ball.
Meehan slams poor performance
"We didn't hit our key points - we didn't get anywhere near them. We had the opportunity to turn it around but I didn't see that performance coming.
"We just never got our game together in the first 40 minutes. In the second half we saw what we were capable of doing. We've got the players I know are capable of doing it and I've got faith in the guys to bounce back - it's only the first game of the season."
Gloucester: Voyce, Simpson-Daniel, Tindall, Fuimaono-Sapolu, Sharples, Robinson, R Lawson, Wood, S Lawson, Somerville, Attwood, Brown, Strokosch, Hazell, Delve. Replacements: Burns for Voyce (79), Molenaar for Tindall (8), Dickinson for Wood (52), Bortolami for Brown (68), Qera for Hazell (61), Dawidiuk for Lawson (77), Capdevielle for Somerville (77), Lewis for E Lawson (72).
Sin Bin: Hazell (40).
Bath: Abendanon, Maddock, Cheeseman, Hape, Carraro, Davis, Claassens, Flatman, Dixon, Wilson, Hooper, Grewcock, Beattie, Salvi, Skirving. Replacements: Banahan for Abendanon (56), Barnes for Claassens (68), Mears for Dixon (49), Bell for Wilson (50), Short for Hooper (50), Faamatuainu for Skirving (50), Little for Davis (79), Bemand for Claassens (79).
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