Giroud scored the only goal to settle a nervy evening at Stamford Bridge as the Blues won 1-0 to move four points clear of Leicester and Manchester United in the race for the top four.
Giroud has now scored four goals since the Premier League restart and has found the net on his last three starts.
The 33-year-old pushed to leave in January but Lampard wanted him to stay and he is now playing a key role for Chelsea in their pursuit of Champions League football next season.
Lampard said: “Even before the lockdown, he came in and was part of a few big results. He has never given me a problem. He has always trained brilliantly.
“When Tammy [Abraham] was really playing well and staying in the team earlier in the season, his professionalism was always good.
“I told him in January I wanted him to stay and he was fantastic how he handled that. And he has continued to do that in the way he trains and the way he plays is important for us.
“When he is in the team you have to try and use his attributes to try and cross the ball and put it in the box. He is an important character and he is scoring important goals for us at the moment.”
Chelsea were not at their best against Norwich but the win means their Champions League fate is in their own hands with two games remaining this season against Liverpool and Wolves.
Lampard added: “We take our three points and we can watch the other teams play this week. Where we are at in the table, three points was everything tonight. It is not easy.
"There was a nervy feeling for understandable reasons, so I am pleased.”