Ant Jefe is in hot water with the law ... the "No Jumper" cohost and rapper just landed behind bars after getting arrested for murder ... TMZ has learned.

Law enforcement sources tell TMZ ... Jefe was busted by LAPD's elite Robbery-Homicide Division and booked for felony murder.

The artist -- whose real name is Maurice Shelmon, is being held on $1 million bail at the LAPD jail. We've reached out to the LAPD for a narrative about what happened ... so far no word back.

Adam 22 tells TMZ, "[Ant has] been a great podcaster for the last year or so and as far as I knew, he wasn’t really in the streets like that anymore, so this was all a huge shock."

As for his career, Jefe is best known as the cohost of the popular hip hop podcast and YouTube channel, "No Jumper." He has also released several rap albums, dropping bars about his life growing up on the tough streets of South Central, Los Angeles.