Tekashi 6ix9ine Gets Out of Federal Prison After 3-Month Stint, on Video

Tekashi 6ix9ine has done his time, and he's back on the streets -- and he's leaving federal prison with a can't-miss souvenir.

The rapper shared a clip from the moment authorities let him back out on the streets Friday morning -- Tekashi's attorney Lance Lazzaro and the BOP both confirmed with TMZ the rapper was let out today.

In the clip, Tekashi seems in high spirits after 90 days in MDC Brooklyn -- coming out the gate hot and dapping up a pal.

He's holding a thick stack of papers ... and a SpongeBob Squarepants doll -- more on that in a minute -- when he walks out and drops his items in a waiting SUV.

Tekashi then shows SpongeBob to the camera ... and says he got former Venezuelan President Nicolas Maduro to sign it -- and even put the date, too. Maduro's been locked up in MDC since the American military went into the Latin American country and extracted him.

Tekashi then puts on a huge chain ... which gleamed almost as bright as his massive smile -- because he couldn't be happier he's out.

Remember ... Tekashi had to return to prison after authorities say he violated his probation. He was accused of possessing cocaine and MDMA last year.