Boyd, who was indicted in March, said he had zero income from 2004-06, when in reality, prosecutors said he made $180,000, $390,000 and $225,000.
The income came long after Boyd's playing career, which ended in the 1970s. Boyd was a contract project manager for a real estate firm in Phoenix.
He was found guilty after a four-day jury trial in Austin, Texas, his home for the last several years, The Arizona Republic reported.
He faces three years in federal prison and a $250,000 fine.
He played two NFL seasons, in 1973 with the New England Patriots and 1974 with the New Orleans Saints.