The match was in the balance at the interval at 2-2 before world No 8 Lee — thought to have one of the best cue actions in the game — showed his silky smooth best with breaks of 121, 77 and 102 to send his opponent back to London.
White scored just 8 points in the last three frames.
David Gray continued his giant-killing act by beating Stephen Hendry 5-3 to reach the semifinals.
Prior to this tournament, world No 30 Gray was best known for knocking Ronnie O’Sullivan out of the 2000 World Championship. He has added local favourites John Higgins and Hendry to his list of scalps this week — as well as Mark King — in reaching his first ranking event semifinal.
The 23-year-old from Morden in Surrey — a practice partner of Jimmy White — believes he has under-achieved since turning professional in 1996 and is delighted to be challenging for a major title.
Today’s match was an unattractive affair with neither player able to live up to the standard they had set in the earlier rounds.
World No 5 Hendry had his eyes set on a third Regal Scottish title after thrashing Ali Carter 5-0 last night and was disgusted with his performance against Gray.
Hendry’s exit means that there are no Scottish representatives remaining — or any in the top six of the world rankings.
In the afternoon session’s other quarter-final, 1995 world championship runner-up Nigel Bond thrashed fellow experienced campaigner Dave Harold 5-1 to reach his first semi since the 1997 Thailand Masters.
World No 23 Bond, from Derbyshire, was off to a flying start with a 131 total clearance in the first frame and never looked back — finishing the contest in the sixth with runs of 43 and 26.
Completing the semifinal line-up is Peter Ebdon, who edged out Australia’s Quinten Hann 5-4 to set up a match with David Gray.
Defending champion Ebdon made the highest break with a 117 in the seocnd frame but Hann - who failed to get past the quarter-final stage at the fifth attempt - will regret missing a simple blue to the centre pocket which would have put him 4-2 up.
A break of 50 put Ebdon in control of the decider then his opponent twice went in-off in attempting to pot reds.
Semifinals lineup: Stephen Lee v Nigel Bond; David Gray v Peter Ebdon