10/29/24 6:52 AM PT -- Attorney Shawn Holley is strongly denying allegations Tory Lanez brought in an ethics complaint he filed with the State Bar of California last week.

TMZ has learned of a letter sent by Holley's counsel to the State Bar in November 2023 ... saying in no uncertain terms that Holley "has no relationship whatsoever with Roc Nation." The letter goes on to emphasize "Ms. Holley has never represented Roc Nation, nor has Roc Nation ever been a client of our law firm."

As for Tory's allegation Holley abandoned him at a critical point of his trial ... in one of his previous court filings Tory revealed emails between Holley and himself, which made it clear she did not want to move forward with a "completely new and different defense" that she was unwilling to advance -- and also that she had a scheduling conflict with the trial date.

Holley's attorney's letter to the State Bar reaffirms both of those facts.

Tory Lanez is ripping his former attorney apart in a formal ethics complaint to the State Bar of California ... claiming she didn't have his best interest at heart when she represented him in his criminal case over the Megan Thee Stallion shooting!!!

TMZ Hip Hop obtained Tory's complaint, in which he says his former attorney Shawn Holley abandoned him when the going got tough in his criminal case -- but not before paying her a few pretty pennies!!!

The incarcerated "Say It" singer claims he took on Holley to represent him without knowing she had business ties to Megan's record label, Roc Nation.

Tory cites Hulu's hit series "Reasonable Doubt" as the source of her conflict of interest. He says Holley served as one of the principal producers on the show, which is loosely based on her life as a celeb attorney.

Megan and Beyoncé's Grammy Award-winning collab "Savage (Remix)" was featured in season 2 of the show, as was a track from Holley's daughter Nayanna, who has sung backup for Beyoncé in the past.

Tory says Roc Nation CEO Desiree Perez was allowed to assist Megan in giving police statements, and claims Holley left him high and dry when she quit representing him on December 18 ...  just 5 days before the guilty verdict ... but after Tory says he paid her between $200K-$300K to retain her services!!!

Tory says his refusal to take a guilty plea caused Holley to neglect fighting for his innocence, including by allegedly telling his DNA expert not to perform extensive studies on the gun after he insisted he never touched it.

Tory believes Holley was acting on the orders of Roc Nation to force him to plead out, and when it didn't work, she withdrew under the pretense that a witness accused her of bribery to affect her testimony on Tory's behalf -- which Tory says was never true.

He's now demanding the California State Bar discipline Holley for the alleged ethical breaches and wants her to return the money he paid her.

Tory may have an uphill battle on his hands ... Holley tells TMZ she's heard this song from Tory before, saying "Mr. Peterson brought these meritless claims to the State Bar over a year ago and they were summarily rejected and the matter was promptly closed. His actions to publicize this failed effort are likely tied to the appeal of his criminal conviction, for which I wish him well."