"Workaholics" star Blake Anderson is expected to make a "full and complete" recovery from his spine-crushing roof jump ... after going under the knife in L.A. yesterday ... TMZ has learned.

As we previously reported, Anderson suffered a fractured spine last weekend ... after he jumped off of his roof and landed back-first on a beer pong table (footage below).

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Now, a rep for the show tells TMZ ... "Anderson underwent successful back surgery. We're pleased to report that the prognosis is for a full and complete recovery."