Yes, CAMPAIGNED is a Scrabble word!

Letter values in Scrabble US: C 3, A 1, M 3, P 3, A 1, I 1, G 2, N 1, E 1, D 2.

Is it a valid word?

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

run, stand, or compete for an office or a position
exert oneself continuously, vigorously, or obtrusively to gain an end or engage in a crusade for a certain cause or person; be an advocate for
go on a campaign; go off to war

Also: take the field.