Kaneie was born the third son of an influential person, FUJIWARA no Morosuke, was appointed to the Jugoinoge rank (Junior Fifth Rank, Lower Grade) in 948, and was permitted to enter the Tenjo no ma room in Seiryo-den in 949 when he was only 10 years old.
実力者藤原師輔の三男に生まれ、天暦2年（948年）に従五位下に叙され、翌天暦3年（949年）には10歳にして昇殿を許された。