A foundation player at the establishment of the professional code in Sydney in 1908 he played one game only for the Kangaroos, the 2nd Test against New Zealand in Brisbane in May 1908. This was the 2nd international rugby league appearance by an Australian side. Watson played that day at in the centres outside of the legendary Dally Messenger.
Five former Wallabies had debuted for the Kangaroos in the inaugural Test three weeks earlier, Watson's league Test debut that day with Bill Hardcastle made them the 6th and 7th Australian dual code internationals.
Since his sole rugby league Test appearance was made as a 1908 rebel  before a Brisbane club competition began in 1909, Watson like Doug McLean, Snr. was a Kangaroo with no rugby league club career.