The former top-ranked German didn’t drop a set against the former French Open winner from Latvia, winning 6-3, 6-3 in 68 minutes on Centre Court.
“It was a tough match, but I am happy I am through,” Kerber, a two-time grand slam winner, said in a post-match televised interview after advancing to her first championship match at the All England Club since 2016.
One of the best defenders in the women’s game, the left-handed German stifled her opponent’s attacking game, as she won the match hitting 10 winners and making just seven unforced errors.
The erratic Ostapenko, who put up a fight in the final stages of the match, produced 30 winners but was undone by 36 unforced errors.
Kerber plays the winner of the other women’s semifinals between seven-time winner Serena Williams of the US or Germany’s Julia Goerges for the Wimbledon title on Saturday.
After a breakthrough 2016, during which she won the Australian Open and US Open and rose to No. 1 in the world, Kerber struggled with the weight of expectation in 2017, as she dropped out of the top 20 for the first time in five years.
In November, Kerber announced she had parted ways with her long-time coach, Torben Beltz, and hired Wim Fissette, the Belgian who used to guide former world No. 1 Kim Clijsters.
The change paid off, with Kerber now playing for the Wimbledon title after a quarterfinals spot at Roland Garros last month and a semifinal place at the Australian Open at the start of the season.
A ferocious ball-striker, the 21-year-old Ostapenko stunned the tennis world last year when she beat title favorite Simona Halep from a set and a break down to become the first unseeded player in the Open era to win the Roland Garros title.
Ostapenko had started nervously in her first Wimbledon semifinal, serving a double fault in the first point of the match.
After saving a break point in the opening game with a blistering double-handed backhand, Ostapenko held. Another break point was saved at 2-2, but she succumbed on the third, this time at 3-3 with a baseline error.
Shaking her head, Ostapenko seemed rattled, as she got broken for a second time as Kerber took the first set, 6-3 in 34 minutes.
Down a set and a break, just like she had been in Paris last year against Halep, there was to be no resurrection this time for Ostapenko on the low-bouncing grass.
Serving at 3-0 down in the second set, Ostapenko seemed to have completely lost her focus as she decided not to chase a high ball that landed on the line. But she recovered, and got a huge cheer from the Centre Court crowd as she eventually managed to hold serve.
Down break point at 4-1 down, a dejected Ostapenko got broken after a sloppy forehand wide.
Serving for the match leading 5-1, Kerber failed to take the first match point as Ostapenko cracked a backhand winner and then set up a break point with a big return.
After breaking her opponent for the first time, Ostapenko held.
Serving for the match for a second time, Kerber played another nervous game, having to save a break point before taking the match on Ostapenko’s 36th unforced error.