Yes, IGNORANT is a Scrabble word!

Letter values in Scrabble US: I 1, G 2, N 1, O 1, R 1, A 1, N 1, T 1.

Is it a valid word?

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

uneducated in general; lacking knowledge or sophistication
uneducated in the fundamentals of a given art or branch of learning; lacking knowledge of a specific field
unaware because of a lack of relevant information or knowledge