Bill Cosby has weighed in on the drama over his one-time costar, Phylicia Rashad, and her new bosses at Howard University ... agreeing that if they can her, they gotta refund him.

The freshly-released Cosby tweeted about the fallout from Phylicia's controversial comments last week -- in which she ecstatically celebrated Bill's conviction being overturned, calling it "justice" -- and he did so by simply concurring with another person's POV on the sitch.

Singer/actress Stephanie Mills actually spilled on how she felt about it, writing ... "I love you @phyliciarashad ❤️❤️❤️. If it’s true that Howard University wants to terminate her Position  because they feel her comments about Mr. Cosby were insensitive, then they should give back the millions of dollars that he donated to the university."

Cosby responded to that quite simply, writing ... "Thank you @iamstephaniemills your voice has always been powerful!" So, in other words, he seems to be fully in her corner on that.

A quick note ... it's not entirely clear how much, if any, dough Cosby has given Howard -- there doesn't seem to be any hard numbers on a donation. That doesn't mean he hasn't chipped in though -- and we know he's been generous when donating to HBCUs.

He famously gave Spelman College $20 million in 1998 -- also, he's an honorary degree holder at Howard. So, it's not outside the realm of possibility he's lined their pockets before.

The funny thing about Bill rushing to Phylicia's defense here ... we're almost certain she doesn't want it -- at least not publicly anyway. She low-key put this matter to bed this past week ... removing her "FINALLY" tweet, and even apologizing to the Howard student body.

So, BC reopening the scab like this probably isn't doing her any favors. If anything, she probably doesn't want Bill's name and Howard brought up in the same sentence around her at all. BTW ... it doesn't look like Howard will fire PR ... they admonished her and that's it.