Due the postponement of the Olympic Games, some of the Irish team members fell out and the Irish Equestrian Federation decided not to send a team to Tokyo.
Instead Holstein represented Ireland individually at the 2020 Olympic Games for the fourth time in her career.
She competed aboard the home-bred mare Sambuca finishing in 37th place.
Her mother Gisela Holstein is a horse trainer and an international dressage judge.
Her brother Erik Holstein competed in showing and rein classes.