Heinrich 'the Black' was born in 1074, the son of Welf I, duke of Bavaria and Judith of Flanders. He was the younger brother of Welf II, duke of Bavaria. Heinrich married Wulfhild of Saxony, the daughter of Magnus, duke of Saxony and Zofia of Hungary. He added to the family holdings in Swabia and Upper Italy additional holdings in Saxony through his marriage. He and Wulfhild had seven children of whom five would have progeny, including his eldest son Heinrich 'the Proud', and his daughter Judith who married Friedrich II von Hohenstaufen, duke of Swabia.
Heinrich succeeded his brother Welf II to the duchy of Bavaria in 1120. In 1125 he supported Lothar von Supplinburg, duke of Saxony in the election for German king, and not his own son-in-law Friedrich von Hohenstaufen, father of the future Holy Roman Emperor Friedrich I Barbarossa. Heinrich had strong ties to Lothar, as his son Heinrich 'the Proud' married Lothar's daughter Gertrud von Supplinburg.
Heinrich 'the Black' died aged 52 on 13 December 1126 in Ravensburg bei Weingarten, and was buried in the foundations at Weingarten. He was succeeded as duke of Bavaria by Heinrich 'the Proud'.