The 32-year-old, who last won the showpiece event back in 2005, pushed on from a 12-5 overnight lead to secure his passage through to the final eight.
A break of 68 was enough for Murphy to seal the winning frame, and he will now face Anthony McGill for a place in the semis.
"I think I am playing the best snooker of my life," he told BBC Sport. "It's nice to get through. "[Being so far in front] is difficult to approach but I tried to prepare in exactly the same way as I would normally do and hope I got the chance to get over the line."
Murphy reached the quarter-final stage at The Crucible 12 months ago, before being comprehensively beaten by Ronnie O'Sullivan.