Konta was looking to become the first British woman to reach the Wimbledon final since Virginia Wade lifted the trophy in 1977, but she was picked off at crucial times by Williams, who claimed the last of her Wimbledon titles nine years ago.
Williams, who will face Garbine Muguruza in Sunday's final, broke in the 10th game to clinch the first set and then turned the screw on her sixth-seeded opponent, breaking twice more to wrap up the match.
Konta saved two match points before Williams crunched a forehand past the Briton and then twirled in celebration on Centre Court.
