The hosts were by far the better side in the first half and went ahead when Jeremie Aliadiere collected Tomasz Frankowski's pass and side-footed home.
Wolves had chances to make it 2-0 before King pounced on a loose ball on 65 minutes and beat Stefan Postma with a sweet right-footed strike.
But King marred his day late on when he was sent off for using foul language.
Watford boss Adrian Boothroyd:
"We do regularly shoot ourselves in the foot. We've had a dip in form, but what we've done well is recover.
"If we can learn from it then we'll get better and better as we go along.
"I said I thought we'd get better as the pressure starts to build. Some teams will be on the beach in a couple of weeks' time but we're not."
Wolverhampton: Postma, Edwards, Lescott, Lowe, Ross (Seol 72), Cameron, Ince (Ricketts 36), Kennedy, Naylor, Aliadiere, Frankowski (Cort 72).
Subs Not Used: Oakes, Little.
Goals: Aliadiere 17.
Watford: Foster, DeMerit, Mackay, Carlisle, Doyley, Eagles (Chambers 90), Mahon, Spring (Bangura 87), Young, King, Henderson (McNamee 61).
Subs Not Used: Stewart, Blizzard.
Sent Off: King (85).
Goals: King 65.
Ref: K Wright (Cambridgeshire).