Jonathan, also called Yehonatan, was the son of King Saul and of Ahinoam daughter of Ahimaaz, of the tribe of Benjamin. The Book of Samuel presents him as the king's eldest son, heir to the throne and a military commander. He became David's brother-in-law when David married his sister Michal, and he was the father of Mephibosheth, to whom David later showed kindness.

From the beginning of his father's reign he commanded a thousand men. He struck down the Philistine governor at Geba, openly challenging their rule. In the war of Michmash, when the people had scattered, he went out almost alone with his armor-bearer against the Philistine garrison, passing between the crags of Bozez and Seneh, and killed twenty men; this feat threw the Philistines into confusion and led to Israel's victory. That day, unaware of the oath his father had imposed, he tasted honey; Saul sought to put him to death, but the people refused, recalling that he had brought about this great deliverance in Israel.

After David's victory over Goliath, Jonathan's soul became bound to David's, and he loved him as himself. Although he was his father's heir, he saw David as the future king, was willing to stand aside for him, and made a covenant with him. He pleaded David's cause before Saul, at the cost of his father's anger. The Mishnah in Pirkei Avot (5:16) cites the love of David and Jonathan as the model of a love that does not depend on anything and never ceases.

He fell together with his father and brothers fighting the Philistines on Mount Gilboa, on 28 Elul according to the Midrash. The Philistines hung their bodies on the wall of Beit She'an; the men of Jabesh-Gilead took them down and buried them under the tamarisk at Jabesh. Later, David moved their remains to the family tomb in the land of Benjamin. In his lament, David said that Jonathan's love had been more wonderful to him than the love of women.