The 2021 Engie Open de Biarritz – Singles was the singles event in the 18th edition of the Engie Open de Biarritz, a professional women's tennis tournament played on outdoor clay courts.

Viktoriya Tomova was the defending champion, having won the previous edition in 2019,[1] however she chose to compete in Budapest instead.

Francesca Jones won the title, defeating Oksana Selekhmeteva in the final, 6–4, 7–6(7–4).