Coatbridge, Lanarkshire born left half Robert Pender began his football career with Kirkintilloch Harp and made his debut in senior football with Second Division club Dumbarton, whom he joined in the summer of 1912, his Scottish League debut coming against Vale of Leven that August. Playing at inside left he scored 14 goals in 41 appearances for The Sons, and he played once for St Mirren on loan in February 1914 before a spell with Johnstone, and later the same year with Dumbarton Harp.
In 1916 he joined Raith Rovers and played for both Johnstone and Dumbarton Harp on loan, and then he played for Renton in 1918 before joining First Division club Middlesbrough in 1919 after the end of the First World War, his Football League debut coming at Newcastle United in December 1919, playing ten matches either side of the New Year at left half before a spell of 13 matches at inside left before the season end.
He played in a variety of positions before establishing himself at left half from October 1921, and he managed 36 appearances in 1922-23 before losing his place in September 1923. He played only 5 more matches during the run in but was unable to prevent Middlesbrough’s relegation at the end of the season, whereafter he left Ayresome Park after 10 goals in 110 appearances, and signed for St Johnstone in the summer of 1924, his final club before his eventual retirement.