The Genealogica Comitum Flandriæ Bertiniana names "Balduinum Barbatum" as son of "Arnulfus…et…Ruzelam quæ et Susanna".
He succeeded his father in 987 as BAUDOUIN IV "le Barbu/Pulchrae Barbae" Count of Flanders, presumably under a regency considering his youth although the name of the regent has not yet been identified. Hugues Capet King of France recognised Baudouin's claim to all of Flanders, including the part previously taken by King Lothaire, and also arranged Baudouin´s mother's second marriage to the king´s son and heir, apparently as a reward for Flemish help when he seized power in 987. "Baldwinus marchysus cum matre sua Susanna" donated "villam Aflingehem…jacentem in pago Tornacinse" to Saint-Pierre de Gand, after the death of "Arnulfi marchysi", by charter dated 1 Apr 988, signed by "…Waldberto advocato, Theoderico comite, Arnulfo comite, Artoldo comite, Baldwino comite, item Arnulfo comite…". After Count Baudouin's mother returned to Flanders following her repudiation, France retained Montreuil-sur-Mer, which provoked Flanders into joining a rebellion against King Hugues. The result was the return of Artois and Ostrevant to Flanders, although Ponthieu remained with France. Count Baudouin established control over the northern part of the Ternois, including Thérouanne, Fauquembergues and Saint-Omer, which were previously under the suzerainty of the county of Boulogne. "Susanna regina…cum filio suo Baldwino" donated "alodem suum…in pago Flandrensi…in Holtawa…in Fresnere…in Clemeskirca…in Jatbeka…in Sclefteta…" to Saint-Pierre de Gand by charter dated 1 Jun 1003. Baudouin captured the march of Valenciennes from Germany in 1006, but lost it in the following year when King Heinrich II invaded Flanders and captured Gent. Count Baudouin subsequently arranged an alliance with the German king who, in 1012, helped him install a new bishop of Cambrai, and enfeoffed him with the islands of Zeeland and, in 1015, with Valenciennes. Emperor Heinrich II, however, invaded Flanders again in 1020, supported this time by Robert King of France. Count Baudouin arranged the betrothal of his son to the French king's daughter to help restore good relations. His son rebelled against Baudouin after 1028. Count Baudouin was forced to take refuge in Normandy, where he married the duke's daughter and from where he returned to Flanders with reinforcements. His son submitted, but his father permitted him to rule jointly.
The Annales Blandinienses record the death in 1035 of "Balduinus, gloriosus marchisus". The Annales Elnonenses Minores record the death in 1035 of "Balduinus comes filius Susannæ". 2