Yes, COMMITMENT is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, M 3, M 3, I 1, T 1, M 3, E 1, N 1, T 1.

Is it a valid word?

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

the trait of sincere and steadfast fixity of purpose
the act of binding yourself (intellectually or emotionally) to a course of action
an engagement by contract involving financial obligation
a message that makes a pledge
the official act of consigning a person to confinement (as in a prison or mental hospital)

Not playable in Scrabble US: COMMITTEDNESS.