The American 16-time Grand Slam winner will now play Czech Republic third seed Klara Zakopalova who had little trouble eliminating Dutch hope Richel Hogenkamp 6-2, 6-3.
Williams broke her opponent's serve three times in each set and was never in trouble on her way into the final four.
The second semi-final will pit home favourite Johanna Larsson against Italian Flavia Pennetta after both players won their quarter-final matches in straight sets.
The 24-year-old Larsson, who is looking for her first WTA singles' title, dropped just three games on the way to a 6-1, 6-2 thrashing of Frenchwoman Mathilde Johansson.
Pennetta who reached the fourth round at Wimbledon, and had a career high world ranking of 10 in 2009, also made short work of her French opponent with a 6-1, 6-3 victory over veteran Virginie Razzano.
The 31-year-old from Brindisi won the doubles titles in Sweden along with Gisela Dulko in 2009 and 2010 as she chases her first single's title at Bastad and 10th WTA victory.
Pennetta and Dulko also teamed up to win the Australian Open doubles' crown in 2011.
Collated results from the fifth day of the WTA Swedish Open on Friday (x denotes seeding):
Klara Zakopalova (CZE x3) bt Richel Hogenkamp (NED) 6-2, 6-3
Johanna Larsson (SWE x8) bt Mathilde Johansson (FRA) 6-1, 6-2
Flavia Pennetta (ITA) bt Virginie Razzano (FRA) 6-1, 6-3
Serena Williams (USA x1) bt Lourdes Domnguez (ESP x5) 6-1, 6-1