One hour was all it took for Konta to wrap up a 6-2, 6-2 victory and set up a semifinal against Elina Svitolina. Earlier in the day, No.2 seed Petra Kvitova also advanced, topping her round-robin group after a 6-1, 6-4 win over Barbora Strycova.
Konta confirmed she would finish the year ranked inside the Top 10 following an impressive win against Samantha Stosur in her opening match, and she underlined her status with an even more dominant display second time out.
It did not take long for the Briton to get her nose in front, hooking a passing shot beyond Garcia's reach to break in the third game. A few games later it was the backhand doing the damage, the World No.10 finding the line to stretch her lead further, before wrapping up the set soon after.
Konta handily won the pair's previous meeting, at this summer's Rio Olympics and a run of five straight games in the second set sent her hurtling past the finishing post.
"I really felt I played a very consistent match. I didn't give her many windows [of opportunity] and I'm very happy I managed to do that today," Konta said during her on-court interview. " She has such a big game so I really needed to apply myself on every point.
"Right now, it's just one more match tomorrow. I'm not looking any further than that. I'm going to have a very tough one and looking to compete as best I can."
While Konta takes on Svitolina, in the other semifinal Kvitova meets Chinese No.1 Zhang Shuai.
Kvitova made a flying start against fellow Czech Strycova before encountering some late resistance. However, just as she has so often in her recent resurgence, she found her best tennis when it mattered most, withstanding some late service jitters - and a couple of break points - to take the final three games of the match.
"The second set was a little bit tight. It was really important to serve well in that game, 4-3. I was facing two break points and it was really the key point," Kvitova said in her press conference.
"And I think that from the time that I started to play more aggressive than I did before, the beginning of the second set, so it helped me actually, to face the two break points to get back on the track and play little bit better and to return better as well. But, I mean, overall it was a good match. I think it was - the serve was really good today; helped me a lot as well. I'm happy that I'm in the semifinal for sure."