Charles was a son of Canute IV of Denmark and Adela of Flanders. His father was assassinated in 1086, and Adela fled to Flanders, taking the very young Charles with her. Charles grew up at the comital court of his grandfather Robert I and uncle Robert II. In 1092 Adela left for southern Italy to marry Roger Borsa, duke of Apulia.
In 1111 Robert II died, and Charles' cousin Baldwin VII became count. Charles was a close advisor to the new count (who was several years younger), who around 1118 arranged Charles' marriage to the heiress of the count of Amiens, Margaret of Clermont.
The childless count Baldwin was wounded fighting for the king of France in September 1118, and he designated Charles as his successor before he died in July 1119.
After Charles' death, his second cousin William Clito was briefly count, and then Charles' first cousin Thierry of Alsace became count.
Galbert of Bruges, The Murder of Charles the Good, translated, with an introduction and notes by James Bruce Ross ISBN 0802064795
References
Preceded by:
Baldwin VII
Count of Flanders
Succeeded by:
William Clito