Wendy Williams has a new legal mind on her side ... 'cause famed attorney Joe Tacopina says he's serving as her personal attorney.

Tacopina -- who has represented big stars like President Donald Trump, former Yankee Alex Rodriguez, and most recently A$AP Rocky -- appeared on "TMZ Live" Thursday to talk about it.

Check out the vid ... he confirms he is representing Wendy -- though, as of right now, it's strictly as her personal attorney. Tacopina says he will be at her guardianship case, but guardianship attorneys have to be approved by a judge, so he's still going through that process.

Tacopina says he's making motions as her "counsel of choice," and tells us about a range of potential approaches he has in mind.

Watch the full clip -- he points out a key phrase Wendy's known for was essentially used against her in her frontotemporal dementia diagnosis ... something our own documentary "TMZ Presents: Saving Wendy" goes into detail about.

Tacopina's comments come just a couple days after fans started lining up outside Wendy's assisted living facility to demonstrate for her freedom -- chanting and picketing in the streets.

We were the first to report Joe was interested in becoming Wendy's attorney ... something he told us on the "2 Angry Men" podcast. He made the announcement about representing her on the NewsNation show "Banfield" Wednesday night

Joe told us he watched our documentary ... and, he was nearly moved to tears by it all -- coming away from it believing Williams shouldn't be locked up in an assisted living facility.

As you know ... last month, Wendy was taken from the facility for a competency test at a local hospital, which she passed with flying colors.

Wendy has claimed she's in a prison-like environment in her assisted living facility, and she's signed a legal document to get out of the guardianship -- and, it looks like she's got a new lawyer willing to fight for her.