Watts, star of 'Mulholland Drive' and the 2005 'King Kong' remake, spent time as a child on her grandparents' farm near the village of Malltraeth, where amateur side Glantraeth FC play.
The population of Malltraeth is 400 and the football club typically play in front of crowds of around 40 people in the third-tier Welsh Alliance Division One.
Watts, 47, was reported to be "very excited" about her new position, which came about after club secretary Stan Strickland sent a letter to her agent in Los Angeles.
"She spent three years of her childhood here and attended school in Llangefni before becoming a major film star," Strickland said, in comments published on the BBC website.
"I just thought, 'If you don't ask, you don't get.' She has now got her publicist involved, so we could end up in the New York Times."