Kanye West is showing up for Lil Durk ... making a surprise appearance Thursday at the rapper's federal trial ... TMZ has learned.

Sources with direct knowledge tell TMZ ... Ye is currently inside the downtown Los Angeles courthouse where Durk's murder-for-hire case is playing out.

Kanye's appearance comes just days after Machine Gun Kelly showed up at the trial Monday, sitting in an overflow room to follow the proceedings. MGK and Durk have history ... MGK played guitar during Durk’s 2023 Amazon Music Live performance.

Ye and Durk have worked together too ... Durk has features on Kanye albums "Donda," "VULTURES 1" and "VULTURES 2."

Durk has been in federal custody since his October 2024 arrest in connection with an alleged murder-for-hire plot.

Federal prosecutors allege Durk sought revenge after his friend and fellow rapper King Von was fatally shot in 2020 outside an Atlanta hookah lounge. They claim members of Durk's crew later targeted rapper Quando Rondo in California in 2022 ... though Quando survived and his cousin, Lul Pab, was killed.

Durk has denied wrongdoing and remains in federal custody.

Kanye attended another rapper's federal trial last summer ... showing up to Diddy's sex trafficking and RICO proceedings in New York City.