He is most well known for the legend, first seen in the Récits d'un ménestrel de Reims (1260s), that after Richard I of England was captured and held for ransom in 1192 Blondel searched for him in Germany and Austria. The story relates that Blondel went from castle to castle singing a particular song (possibly "L'amours dont sui espris"), the imprisoned Ricahrd would reply with the second verse after Blondel sung the first - thus identifying were Richard was imprisoned and then Blondel would (depeneding on the source) either aid the king's escape or report his position back to England.
In reality Blondel is an unknown. His name is attached to roughly 25 works and no more is known. Blondel may have been his name or a nickname, he may have come from Nesle in Piccardy. If the works are correctly identified and dated he was a significant influence on his European contemporaries, who made much use of his melodies. The known works are fairly conventional, especially the poetry.