Yes, JOSEPH is a Scrabble word!

Letter values in Scrabble US: J 8, O 1, S 1, E 1, P 3, H 4.

Is it a valid word?

JOSEPH is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

leader of the Nez Perce in their retreat from United States troops (1840-1904)
(Old Testament) the 11th son of Jacob and one of the 12 patriarchs of Israel; Jacob gave Joseph a coat of many colors, which made his brothers jealous and they sold him into slavery in Egypt
(New Testament) husband of Mary and (in Christian belief) the foster father of Jesus

Also: chief joseph.