The 28-year-old missed the last three months of the 2001/12 campaign after undergoing ankle surgery, and his absence proved costly as the Midlands club flirted with relegation.
However, Lambert, who replaced Alex McLeish at the helm last month, is relishing the prospect of unleashing the former Ipswich, Charlton, Tottenham and Sunderland marksman on the rest of the league next month.
He told Villa's official website, www.avfc.co.uk: "Darren will be huge, absolutely huge. He's a goalscorer. Every team needs them. You can't just rely on one guy to score you the goals, but his influence at the football club is huge as a result of what he has done in his football career up to now.
"He had a fabulous goalscoring record at Sunderland and if you look at it, his goalscoring career here is phenomenal. For England too, he is a threat. He would have gone to the Euros no problem if he had been fit. It is a big plus for us to have him fit."
Bent scored 10 goals for Villa last season before succumbing to injury in February. He joined the club in a shock £24million switch from Sunderland in January 2011 after restoring his reputation with 36 goals in 63 appearances for the Black Cats following a difficult end to his spell at White Hart Lane.