The Ghana-born Norway international broke his duck in sensational style at Carrow Road, reacting first to a cleared corner to smash home a half-volley from fully 30 yards.
Tettey's goal was only his third in league games since he joined French side Rennes in 2009 but he says it is something he works hard on in training.
"I've been hoping to get a goal since I came to the Premier League," Tettey told Sky Sports News.
"I've been practising hard on the training ground and hopefully I got a great goal. When I strike and hit good on the ball I tend to score some great goals. It never happens that often but I am very happy for today."
The victory lifted Norwich into 13th, seven points clear of Saturday's opponents, although Sunderland do have three games in hand.
But Tettey feels their biggest test is trying to find some form away from Carrow Road, starting with next weekend's clash against 15th-placed Swansea.
"It is vital for us. Playing at home, winning 2-0 and the way we played today I think is huge for the team and for our confidence as well," Tettey added.
"But first of all we have to get our away form running as well. At home we feel comfortable, we feel great playing for our fans.
"Now we have to find a formula to get some points away and then I think we'll be fine."