What is the ruling on the marriage contract of a woman marrying herself off with her guardian’s consent; the bridegroom said: "Would you marry me?" and the bride replied: "I do," in the presence of the witnesses of course?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Among the due conditions of a valid marriage contract in Islam is the presence of the bride’s guardian. The marriage is invalid if it was concluded without the guardian’s presence. In fact, this legal guardianship is a due right given by the Islamic Sharee‘ah to the woman’s guardians; hence, it is impermissible for the woman to marry herself off, even if it was with her guardian's consent.

Therefore, such marriage is invalid; as it lacks the presence of the legal guardian representing the bride, or his deputy. The bride’s father is entitled to assign a deputy to marry his daughter off on his behalf as long as he approves of the marriage, and that deputy should be present with the bride while concluding the marriage contract.

Allaah Knows best.