Ekaterina Makarova had no answer to fifth seed Kerber as the German triumphed 6-2 6-1 in an hour and four minutes in Eastbourne on Thursday.
World number nine Kerber built further momentum ahead of Wimbledon, which starts next week, with an impressive showing.
It could have been a different story had Makarova been able to take one of the four break points that came her way in the second game of the match, but Kerber dug deep to hold and never looked back.
She reeled off four games in a row to win the first set in 38 minutes and Makarova was unable to respond in the second, as Kerber broke twice to lead 3-0 and secured a further two breaks to set up a clash with Wozniacki.
Dane Wozniacki, seeded eighth, was made to work for her place in the semi-finals as she beat Camila Giorgi 6-7 (7-9) 6-4 6-2.
Both players claimed a break apiece in the first set and the tie-break was also a tense affair, while included a controversial moment when umpire Alison Hughes halted play with Giorgi 7-6 up after making an incorrect call.
Giorgi was not impressed after she double-faulted when the point was replayed and was warned after smashing the ball into the crowd, but regained her composure to take the set.
A solitary break was sufficient for Wozniacki to level the match and the world number 16 sealed her progress to the semi-finals by breaking twice in the decisive set to complete the comeback.
Madison Keys and Heather Watson will meet in the other semi-final and the latter will have the benefit of a day off on Thursday.
Watson was due to face second seed Petra Kvitova, but the Czech withdrew before the match due to a thigh problem she hopes will not keep her out of Wimbledon.
Kvitova tweeted: "So sorry to pull out of my QF against Heather. Was really enjoying Eastbourne. Will get treatment and hope to be ready for Wimbledon."
Keys, meanwhile, came out on top against fellow American Lauren Davis, who was beaten 6-2 6-1.
The teenager sent down six aces and only afforded her opponent two break point opportunities in a convincing performance to secure her third semi-final appearance of the year.