Q) Recently there have appeared in the marketplace women's shoes which from the front look like men’s shoes, sandals with a separate space for the big toe, but from the back and the bottom they look like women's shoes. Is it permissible to buy them and wear them?
A) Praise be to Allaah.
If they look like men’s shoes, and if a person sees them he will think that they are men’s shoes, then it is not permissible for women to wear them. Similarly, if a man were to find shoes which looked like women’s shoes although the soles and heels looked like men’s shoes, it would not be permissible for him to wear them, because what counts is the way things look. My advice to my sisters is not to wear them, because this is a serious matter. It was reported that the Prophet (peace and blessings of Allaah be upon him) cursed men who imitate women and women who imitate men.
From the fatwas of Shaykh Muhammad ibn Saalih al-‘Uthaymeen for al-Daw’ah magazine, issue # 1757, p. 45