She was the only daughter of Bohemond II of Antioch by his wife, Alice of Jerusalem. She was also Princess regnant of the Principality of Antioch (a crusader state) from 1130 to her death.
She became princess of Antioch when she was only four-years-old, under the regency of Baldwin II of Jerusalem (1130–1131) and Fulk of Jerusalem (1131–1136).
Her mother Alice did not want the principality to pass to Constance, preferring to rule in her own name. Alice attempted to ally with the Muslim atabeg of Mosul, Zengi, offering to marry Constance to a Muslim prince, but the plan was foiled by Alice's father Baldwin, who exiled her from Antioch. In 1135 Alice attempted once again to take control of the principality, and sought a husband for Constance in Manuel Comnenus, at that time the heir to the Byzantine throne. Fulk exiled her again and re-established the regency for Constance.
In 1135 Alice offered Emperor Manuel the hand of her seven-year daughter Constance, which was a concern for the French barons. Fulk of Jerusalem then chose Raymond of Poitiers, a younger son of William IX, Duke of Aquitaine, as future husband for Constance. Neither Alice nor Roger II of Sicily was to learn of this. To get to Antioch, Raymond had to dress up as a pilgrim and a servant, dodging the Scouts of the Normans to prevent them from learning of the agreement with Fulk. In 1136 Raymond arrived in Antioch. Alice was tricked into believing Raymond was going to marry her. This rumor was spread with the help of Patriarch Radulph, but in truth, Raymond didn't want to marry Alice but to kidnap Constance. While Alice was waiting the applicant in the palace, Constance and Raymond were married hastily. Alice retreated back to Latakia, humiliated.
In 1149 Raymond was killed in the Battle of Inab during an expedition against Nur ad-Din Zangi. He was beheaded by Shirkuh, the uncle of Saladin, and his head was placed in a silver box and sent to the Caliph of Baghdad as a gift. Raymond left Constance a 22-year-old widow.
Constance and Raymond had four children (three surviving). Her son Bohemond was just five years old when his father was killed. Therefore, the Patriarch Aimery took over power in Antioch. Baldwin III of Jerusalem was appointed Regent and proposed Constance marry an ally but with no success. Ives Nesle, Count of Soissons (House of Nesle), Walter of Falkenberg (Saint-Omer) and Ralph Merle, Baron from Tripoli were proposed as candidates however, but no decision was made, so they asked Emperor Manuel I to determine her a spouse. Manuel sent John Roger, who had been married to his late sister Maria, but Constance refused him and he had to return to Constantinople. In 1152 Baldwin and Constance were ordered to Tripoli with help from Baldwin's mother, Melisende of Jerusalem to encourage a new marriage to one another. But again, success remained elusive.
Constance remarried in 1153 to Raynald of Châtillon, who also became co-ruler of Antioch. Raynald had been in the service of Baldwin III of Jerusalem. The marriage was, however, unpopular because Raynald was considered an upstart.
Raynald was captured on a rampage in the anti Taurus by Madsch-ed-Din, the Governor of Aleppo, in 1160. Constance then claimed her independent rule over Antioch. The popular party supported her son from her first marriage, the 15-year-old Bohemond; however, Constance did not wish to hand over the Principality to her son, who was now legally old enough to rule. King Baldwin stepped in and had Bohemond made Prince and appointed an old opponent of Raynald's rich and wordly Patriarch Aimery of Limoges as regent. Constance protested against this decision to the Court of Constantinople.
In 1159 Bertha of Sulzbach, wife of Manuel I died, the Emperor married the following year in 1160 to Maria, the daughter of Constance and Raymond. The marriage strengthened the position of Constance, who now held the Regency of Antioch. Raynald was released only 1176.
In 1163 Constance asked the Armenian Kingdom of Cilicia for aid in order to maintain her rule; the citizens of Antioch then rioted and exiled her. She died later that year, allowing Bohemond to take full control.
Constance had one daughter from Raynald:
• Agnes of Antioch (1154–1184), who married king Bela III of Hungary
Some sources [2] believe that Constance and Raynald had another daughter, Joan, possibly the second wife of Boniface I of Montferrat.