The 33-year-old runner won an earlier round at the ECHR, which last July ruled she was the victim of discrimination from the Lausanne-based Court of Arbitration for Sport (CAS).
"This is an important day in my journey as a human being and athlete. It has been a long time coming," said Semenya, who was the Olympic 800m champion in 2012 and 2016 and world gold medallist in 2009, 2011 and 2017 for South Africa.
"In 2009 I stood atop the podium at the Berlin world championships having just been sex tested and knowing that the world was judging my body and questioning my sex. In the 15 years since then I have persevered with dignity in the face of oppression.
"The adversity I have overcome has helped shaped me into a true champion and a compassionate mother, wife, sister, and daughter.
"I hope that the Court's decision will pave the way for all athletes' human rights to be fiercely protected, for once and for all, and inspire all young women to be and accept themselves in all their diversity."
Semenya, later speaking after the hearing ended, added: "The outcome of this case is very important. You need to pave out a way for young women so they cannot face the injustice, the scrutiny of being judged, being dehumanised and being discriminated.
"I don't think this is about my career. It is about me being an advocate for what is right, to voice out for those who cannot fight for themselves."
Semenya, who is classed as having "differences in sexual development (DSD)" but has always been legally identified as female, has refused to take drugs to reduce her testosterone levels since track and field's governing body World Athletics introduced its original rules in 2018.
CAS ruled against her in 2019 and the decision was validated by the Swiss Federal Court in Lausanne in 2020. It declared "fair competition" a "cardinal principle of sport" and said that a testosterone level comparable to that of men gave female athletes "an insurmountable advantage".
'Lived as the woman she is'
Last July, a seven-member ECHR panel ruled, by four votes to three, that the Swiss court's decision constituted discrimination and a violation of Semenya's privacy.
The decision was largely symbolic as it did not call into question the World Athletics ruling nor pave the way for Semenya to return to competition without taking medication.
Swiss authorities, supported by World Athletics, appealed to the European court's 17-member Grand Chamber. Its ruling is not expected for several months but will be binding.
Semenya's lawyer, Schona Jolly, said her client had "lost years of her career awaiting a final determination".
"What this Court says will impact profoundly on her personal and professional life, and indeed, the lives and dignity of many other international sports women."
Semenya, Jolly said, "was forced into illusion of choice, either to safeguard her personal integrity and dignity, and yet be excluded from competing as an elite athlete in the exercise of her profession, or as a healthy woman and athlete to undergo a harmful, unnecessary and supposedly corrective medical treatment".
"Miss Semenya is a woman," Jolly added. "She was assigned the female sex on birth, legally and factually. She has always lived as the woman she is."
Last year, World Athletics altered its rules. DSD athletes like Semenya now have to reduce their amount of blood testosterone to below 2.5 nanomoles per litre, down from the previous level of five, and remain below this threshold for two years.
World Athletics also removed the principle of restricted events for DSD athletes, meaning that they are barred from all distances unless they meet the testosterone criteria.
