The German, who was runner-up to Serena Williams two years ago, triumphed 6-3 6-3 on Centre Court and is now one win away from a third grand slam title.
This semi-final was billed as attack versus defence and it was the solid, reliable manner of Kerber that prevailed as she let an erratic Ostapenko, who was going for winners almost every shot, hand her a swathe of free points.
Ostapenko won the French Open in 2017 by playing in this manner and knows no other way, but she had an off day and, despite hitting 30 winners, it was her 35 unforced errors which cost her any chance of progressing.
Kerber, who spent 34 weeks at world number one between 2016 and 2017, could be set for a rematch with Williams if the eight-time champion can get past Julia Goerges in the second semi-final.
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