Romney has been campaigning for the Republican candidate Scott Brown.
TPM checked in with Fehrnstrom after speaking with the town clerk in Belmont, Mass., who confirmed that Romney voted in the Dec. 8 special election.
He used an address in Belmont that matches the address of a home where their son Tagg lives.
According to the Boston Herald, Romney sold his six-bedroom home in Belmont for $3.5 million.
A report in the Associated Press last April said Romney sold his home in Utah for $5 million but was keeping a $10 million summer home in New Hampshire and a $12 million home in La Jolla, CA.
Additional reporting by Zachary Roth.