The Saints came through a rigorous test of their mettle at Kingsholm after being virtually unplayable in the first half.
Northampton's win got their season off to the right start as Samoan centre George Pisi got two tries and England hooker Dylan Hartley added the third.
Fly-half Ryan Lamb landed a penalty and three conversions against a penalty try for Gloucester and four penalties and a conversion from Freddie Burns.
It did not help Northampton's cause that debutant back row GJ van Velze and replacement prop Paul Doran-Jones were both sin-binned in the last 15 minutes, giving Gloucester a two-man advantage as they tried to win a match they had seemed likely to lose.
Mallinder said: "We were playing away from home at a club notorious for being difficult to beat on their ground. We didn't have to overplay but we lost the ball at times which was annoying."
England flanker Tom Wood, who was out with a toe injury from March to this summer, came through a full match, and Mallinder said: "We have been drip-feeding him back in over the last couple of weeks and he is really pleased.
"We really missed him last season. We are just being cautious with him and we are pleased he is back and playing well. He is important to the team.
"He has played 80 minutes now and he will want to play next week. We know the potential of Tom Wood and hopefully he can have a big season for us."
Gloucester, under new head coach Nigel Davies, got themselves back into the match after the break, but it was too much of an uphill battle even after Northampton went down to 13 men.
Their penalty try came from a collapsed scrum and, with ex-England ace Mike Tindall linking up with rising star Billy Twelvetrees at centre for the first time, plus four other debutants in the 22, there was bound to be some bedding in.
Davies said: "I am really disappointed that we worked so hard to get back into that game and we couldn't finish it off.
"I think the pleasure I take from that is that we don't need to panic.
"If we play our game and play to our structures and play in the right areas, we have the capabilities of beating sides.
"Northampton are, without a shadow of a doubt, one of the best teams in Europe and we were very close to beating them today."
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