The home side opened up a lead over the first 20 minutes as Stephen Myler added three penalties, making the most of a string of errors from Gloucester.
© Getty Images
The visitors were handed a chance to get back into the game before half time as Tom Wood was sent to the sin bin for collapsing the maul, allowing Billy Twelvetrees to get them on the board with a penalty.
The wet conditions at Franklin's Gardens continued to make it difficult for both sides to create try-scoring opportunities after the break, but Myler maintained his accuracy with the boot, kicking a further six points to leave Northampton 12 points up inside the final 15 minutes.
The visitors finished the match a player short as Yann Thomas was judged to have deliberately knocked on while trying to clear a kick forward from Saints, earning himself a yellow card.