The sixth seed has previously reached the final on six occasions, but he produced a lacklustre performance as King completed a convincing victory at the Winter Gardens.
But Gary Anderson, Adrian Lewis and Peter Wright are all safely through to the last-16 after they claimed opening wins on the second day of the tournament.
A wasteful display of finishing from Wade began in the very first leg as three missed darts at a double allowed King to hold throw.
The experienced King was punishing regular errors from his erratic opponent and took out 100 on double 10 to establish a 4-1 lead.
Wade was unable to close the gap, with King calmly compiling his checkouts, and the Suffolk man sunk his dart into double four to inflict an upset loss on Wadetopics from