Westwood's long-range effort capped off an impressive comeback from Villa, who had found themselves two goals down after 11 minutes at The Hawthorns.
Lambert stated his delight at Westwood's overall performance, as well as his late goal.
"Ashley was excellent the whole night. Even in the first half I thought his passing was excellent," he said.
"His goal was a terrific strike. He's got superb technique. He was worthy of that goal because I thought he was outstanding."
Fabian Delph, Andreas Weimann and Gabriel Agbonlahor were all introduced three minutes before the hour in the game, with their side two goals down.
Lambert believes the trio's introduction helped Villa rescue a point, although he explained he was unable to start the trio.
"We couldn't (start the three players). It was an absolute impossibility. They only trained on Friday," he said.
"It was a big ask to put them in. I trust the team I picked at the start to go and perform. I always will do that. I never have any regrets with any decisions.
"But we needed a goal at a certain time in the game. I was actually going to put them on a bit later.
"(Assistant manager) Ian (Culverhouse) and I had a chat at half-time and decided to make the changes pretty quick. We threw them on and thankfully it worked."
The draw leaves Villa 12th, with one win from their last six Premier League matches.
