Watson was a Democrat, and was first elected to the state house in 1884, but his eligibility was challenged due his previous residence in Philadelphia. As a result, did not take his seat and waited eight years, until 1892, to seek office again. Then he was elected to the state senate and served in the 1893/94 session and the 1895/96 session, when he was the Speaker. The 1894 elections, however, resulted in a Republican State House and a Republican Governor. Regardless, the state senate kept its Democratic majority, and when Governor Joshua H. Marvil died, the Speaker of the state senate succeeded him. Watson assumed the office of Governor of Delaware and served from April 8, 1895 until January 19, 1897.