Géza I (c. 1040 – 25 April 1077) was King of Hungary from 1074 until his death.

He is the eldest son of King Béla I.

His baptismal name is Magnus.

When his father dies in 1063, Géza's cousin, Solomon, acquires the crown with German assistance, forcing Géza to leave Hungary.

Géza returns with Polish reinforcements and makes an agreement with Solomon in the spring of 1064.

In the treaty, Géza and his brother, Ladislaus, acknowledge the rule of Solomon, who grants them their father's former duchy, which encompasses one-third of the Kingdom of Hungary.

He closely cooperates with the king hereafter, but their relationship becoms tense from 1071.

The king invades the duchy in February 1074 and defeats Géza in a battle.

However, in the decisive battle of Mogyoród Géza emerges the victor on March 14, 1074.

He soon acquires the throne, although Solomon maintains his rule in the regions of Moson and Pressburg (Bratislava, Slovakia) for years.

Géza initiates peace negotiations with his dethroned cousin in the last months of his life.

His sons are minors when he dies, thus he is succeeded by his brother, Ladislaus.