Morrison played as a schoolboy for, Dollar Academy, where he captained the 1st XV. He has represented Scotland at under-21 level.
Morrison played in all four tests against Australia in 2004. He scored his first international try in the win over Japan at McDiarmid Park in the same year.
He has been recalled to the Scotland team for the first time in four years, for the Calcutta Cup tie against England on 8 March 2008, following some excellent displays for his club side, Glasgow. Morrison's previous request for Japanese citizenship had been rejected, ending his dream of him playing for his boyhood hero's.