The world number two, who is attempting to retain his title in Tokyo, won nine of the last 10 games against the previously in-form American to earn his 65th win of the season and seal a spot in Sunday's final.
That tally takes him clear of nemesis Novak Djokovic, who has registered two of his 64 wins this season in grand slam finals against Nadal.
Sunday will be the Majorcan's 10th Tour final of the year and if he wins, it will be his first hard-court triumph since winning this event a year ago.
He will face a stern test from Murray, though, the man he has beaten in the semi-finals of Wimbledon and the US Open this year.
Murray, eyeing Roger Federer's third-placed ranking before the end of the season, took just 81 minutes to ease past Nadal's compatriot David Ferrer in the day's other semi-final.
The in-form player on the Tour, the 6-2 6-3 success was Murray's 11th in a row and he has lost just one of his last 23 matches.
In fact, Nadal has inflicted two of his last three defeats on him, something he will need to remedy on Sunday if he is to back-up last week's win in Thailand, but this performance against Ferrer suggested he was ready to do that.
Murray's incessant hitting from the baseline, normally a hallmark of Ferrer's game, forced the world number five to concede his serve twice in the first set, allowing the Scot to take it at a canter.
Ferrer's hopes of fighting back in the second suffered an instant blow as Murray cashed in three break points in the very first game.
That was all he needed and, after holding serve impressively and displaying none of the frailties that appeared on serve during his quarter-final win over David Nalbandian on Friday, he won inside 81 minutes.