Donovan McNabb -- I'M FREEEEEE ... Sorta.

Donovan McNabb is officially OUT OF JAIL ... but he's not completely out of the woods -- 'cause the ex-NFL superstar will spend the next 72 days on house arrest ... TMZ Sports has learned.

As we previously reported, McNabb began his 18 day jail sentence in Arizona right after Thanksgiving ... stemming from his DUI arrest back in June (his 2nd DUI conviction in 2 years).

He did the time behind bars ... and now he'll finish up his sentence by spending the next 72 days confined to his home.

As part of his sentence, McNabb must also complete 30 hours of community service ... though his lawyer has said it'll be cake because D.M. does a TON of charity that isn't court ordered.