Starting with Kebiishi no jo (second officer of the imperial police bureau) of Fifth Rank, Morotaka was his father's patronage appointee to the post of a Kokushi (provincial governor) of Kaga Province who was remotely appointed, having his younger brother FUJIWARA no Morotsune as his mokudai (deputy kokushi, or a deputy provincial governor).
検非違使五位尉から、父の引き立てで安元元年（1175年）12月29日(旧暦)、加賀国国司となり、弟の藤原師経を目代として遙任する。