Cobb, 30, put his legal career on hold to join the RFL's full-time pool, and was among the officials for England's 2015 series against New Zealand.
However, he is the third official to quit Super League in a year, following Matt Thomason and George Stokes.
"The RFL would like to thank Joe for his efforts," chief operating officer Ralph Rimmer said in a statement.
"We wish him the best of luck pursuing his professional ambitions."
Match official Joe Cobb has retired from rugby league refereeing, according to the Rugby Football League.