Williams was twice pegged back in a hard-fought opening four frames before a series of Walden errors post-intermission opened the door for the Welshman to find his stride and take three in a row.
Walden was playing the better snooker early on, clearing to 95 for 1-1 before an agonising miss on the final green denied him the lead after he had won two snookers to claw back what appeared to be a lost cause in the third.
The 10th century of the tournament, a lovely 112 clearance, made it 2-2 but also served as Walden’s apex: Williams took the lead for a third time with a 67 before costly errors from the Englishman gave the world number three second chances to take frames six and seven to advance.
Awaiting him in the last eight is Perry, who stunned 2010 Crucible winner Robertson in a five-frame whitewash with ruthlessly efficient play.
After entering a 2-0 lead, runs to 51 and 75 ended a one-sided half-session and though Robertson fought hard for the snookers he needed to stay in the match in frame five, he eventually succumbed to the shut-out.
Ali Carter also won 5-0 against the man he defeated in this year’s World Championship semi-final, Stephen Maguire.
‘The Captain’ book-ended his pre-interval dominance with an opening frame half-ton and a century in the fourth before constructing a series of smaller builds to grind out the Scot in the fifth.
And Stuart Bingham continued his good form this year with a confident 5-1 victory over Jamie Cope, who had sent defending champion and world number one Mark Selby packing in the previous round.
Cope got sufficient table time to take the third frame of the contest, but otherwise found himself boxed out by Bingham.
The Essex man scored 78 and 89 on his way to victory.
Stuart Bingham v Shaun Murphy
John Higgins v Ali Carter
Mark Williams v Joe Perry
Judd Trump v Graeme Dott