The World number one beat Croatian Donna Vekic 6-3 4-6 7-6 (7-4) at the Porsche Tennis Grand Prix.
Osaka will now face Anett Kontaveit, who was able to progress after Victoria Azarenka retired.
Petra Kvitova will face Kiki Bertens in the other semi-final.
French Open champion Gauff knocked out by Potapova in third round
Defending French Open champion Coco Gauff has been knocked out of the Grand Slam following a 4-6 7-6(1) 6-4 loss to Anastasia Potapova in the third round at Roland Garros on Saturday.
Sabalenka sees off Kasatkina to reach French Open fourth round
Aryna Sabalenka has cut through the French Open chaos as the world number one beat Australia's Daria Kasatkina 6-0 7-5 on Saturday to seal her place in the fourth round after seismic upsets in the previous two days at Roland Garros.
Parry stuns Anisimova to reach first Grand Slam fourth round at French Open
Diane Parry, the last Frenchwoman standing in the French Open women's draw, has pulled off a stunning 6-3 4-6 7-6(3) victory over American Amanda Anisimova on Saturday, advancing to the fourth round of a Grand Slam for the first time in her career.
Osaka survives three-set scare against teenager Jovic
Naomi Osaka has dazzled with an all-gold outfit but had to dig deep for a hard-fought 7-6(5) 6-7(3) 6-4 victory over American teenager Iva Jovic on Saturday to reach her first-ever French Open fourth round.
Cobolli cruises past Tien in straight sets to snap American's winning run
Italian Flavio Cobolli has dismantled American Learner Tien 6-2 6-2 6-3 on Saturday to advance to the French Open fourth round in commanding fashion.
The Ministry of Foreign Affairs is advising UAE nationals and residents to avoid non-essential travel to Uganda, the Democratic Republic of the Congo and South Sudan due to the evolving public health situation related to Ebola.
Dubai Police have foiled a major robbery that involved eight suspects attempting to steal rare luxury oud valued at AED 12 million.
Authorities have confirmed that the public health situation in the UAE remains stable as it reviews the Ebola virus developments and reinforces its preparedness.
