"In the two years that I've been here he's been colossal," Lambert told BBC Radio Norfolk.
"He has created a niche for himself that lad, and coming here was probably the greatest career move he's made."
He added: "He is a major figure at this football club, but he's not one of those lads that thinks he's arrived, he keeps working hard."
Holt
was signed from Shrewsbury in 2009
by Bryan Gunn following Norwich's relegation to League One, but it was not until Lambert's appointment, two games into the 2009/10 season, that he was made captain.
He went on to score 30 goals in his maiden term at Carrow Road, lifting the League One title and earning a return to the Championship at the first attempt.
"Not bad is it? It's gone well, I didn't think I'd get them in this quick succession but I have," Holt added.
"It's just a measure of what a good team I've got playing behind me that I can achieve that tally."
It's unreal, he's been doing the business all season
Simeon Jackson on Grant Holt
Questions had been raised over Holt's ability to make the step up to the Championship following previous less fruitful second-tier spells with Sheffield Wednesday and Nottingham Forest.
But after netting 19 league goals this season, including hat-tricks against Scunthorpe and Ipswich Town, he has proved any previous doubts unfounded.
Team-mate Simeon Jackson, who also bagged a treble against the Iron, said Holt's achievements are remarkable.
"It's unreal, he's been doing the business all season, it's the last few games now and hopefully he can keep doing it," said Jackson.
And despite Holt scoring three and reaching his half-century on Saturday, he was happy for Jackson, who had not scored since October, to take home the match ball for his treble.
"He can have it, it's not about the ball, it's about getting the win today," added Holt.
"To be honest I'm more pleased for Simeon than I am for myself."
"That's exactly why he's captain," replied Jackson.
Source: BBC Sport
Source: BBC Sport