Walk says, "“There has never been a single HR claim against me at any time during my 25+ year career, spanning three major companies.” He told Deadline, “I have consistently been a supporter of the women’s movement and this is the first time I have ever heard of this or any other allegation — and it is false.”

One of Charlie Walk's former employees claims "The Four" judge repeatedly groped her, and sent her vulgar, sexually charged text messages ... ultimately forcing her to quit the music biz.

The accuser, Tristan Coopersmith, claims Walk -- currently prez of Republic Records -- harassed her while they worked together at Sony Music. In an open letter, Tristan wrote, "For a year I shuddered at the idea of being called into your office, where you would stealthily close the door and make lewd comments about my body and share your fantasies of having sex with me. I was 27."

She says she repeatedly reminded Walk, her boss at the time, he was married with kids, but claims it had no impact. Tristan claims Walk would grab her leg under the table dinner meetings ... sometimes while his wife was sitting across from them.

She detailed one alleged encounter ... "And then there was that event at your swank pad when you actually cornered me and pushed me into your bedroom and onto your bed. The bed you shared with your wife… your wife who was in the room next door. You being drunk and me being 6 inches taller was my saving grace."

Tristan quit the music biz 8 years ago, and is now a psychotherapist. She posted the letter on her website. Tristan says she's forgiven Walk and hopes he can change his ways.