 Born in Stoneybatter but raised in the North Wall area of Dublin, Cullen was introduced to Gaelic football by the Christian Brothers at St. Laurence O'Toole National School and later at the North Strand Vocational College.He joined the O'Connell Boys club straight after finishing his schooling and enjoyed a club career that spanned four decades from 1959 until 1982.Cullen combined both Gaelic football and soccer in his youth and developed a reputation as a fine soccer goalkeeper when he played in the local street leagues.