Donovan McNabb -- Joining NFL Network ... as a Broadcaster

It seems Donovan McNabb's playing days are over ... TMZ has learned the quarterback has inked a deal to join the NFL Network as a broadcaster.

TMZ spoke with McNabb's rep Mark Lepselter who confirms McNabb has officially signed on ... adding, "He is going to be a part of their 'Playbook' show, as well as other platforms on the network."

We're told McNabb will tape the show in both New Jersey and Los Angeles.

Lepselter says Donovan is serious about his new gig ... telling us, "[Broadcasting] is something that he is going to devote 100% of his attention to."

"With that said, he does have some other areas in his life that he wants to pursue in this next phase ... business interests ... real estate in particular."