The Belgium international will change the colour of his curly afro if £25,000 is raised for charity Everton in the Community.
"Our fans have already given thousands of pounds to support Everton in the Community but there's still a long way to go, so I hope that my silver hair challenge will help to bring in lots more money and make a difference," Fellaini told the club's official website.
"I've never done anything like this before but I am happy to help this brilliant charity. It helps so many people and I want to help them too."
The 25-year-old has netted 11 goals in 27 appearances for the Toffees this season.