Yes, HISTORY is a Scrabble word!

Letter values in Scrabble US: H 4, I 1, S 1, T 1, O 1, R 1, Y 4.

Is it a valid word?

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

the aggregate of past events
a record or narrative description of past events
the discipline that records and interprets past events involving human beings
the continuum of events occurring in succession leading from the past to the present and even into the future
all that is remembered of the past as preserved in writing; a body of knowledge