Arthur Millar was born in Rossie Island, Montrose, in 1877. He played football for his hometown club before moving to England in 1896 to sign for Southern League club Millwall Athletic club. He remained with Millwall for five seasons, captained the team, and was reportedly very popular with the supporters.
He was part of the team that eliminated reigning Football League Champions, Aston Villa from the 1899-1900 FA Cup after two replays to reach the semifinal, in which Millwall lost to Southampton to after just one replay. Villa were sufficiently impressed with Arthur that they signed him, but he made only ten appearances in the First Division before returning to Millwall, initially on loan.
He finished his career with a season at Brighton & Hove Albion where he was remembered as a “hard, resolute defender”. Arthur played 36 matches for the Seagulls in 1904-05 scoring 1 goal.