;1988–1990 Watson decided to run in Rhode Island's 22nd Senate District, based in East Greenwich and Warwick. In 1990, he ran for re-election but lost to Democrat Michael Lenihan by a narrow margin. ;1992–2000 After redistricting, he decided to run in the Rhode Island House of Representatives in 1992 to the 43rd district. He defeated Democrat Linda Seiler and Independent David Zartarian. In 1994, he won re-election to a second term defeating Democrat David Zartarian. In 1996, he won re-election to a third term unopposed. In 1998, he won re-election to a fourth term defeating Democrat Gregory DeGroot. In 2000, he won re-election to a fifth term against Reform party nominee Timothy Miller. ;2002–present Upon redistricting and downsizing of the RI House from 100 to 75 members in 2002, Watson ran in the newly redrawn 30th House District, based in East and West Greenwich. He won re-election to a sixth term unopposed. He ran unopposed in 2004 to his seventh term. In 2006, he won re-election to an eighth term with 57% of the vote. In 2008, he won re-election to a ninth term 54%-46%, winning in eight of nine precincts. In 2010, he won re-election a tenth term with 57% of the vote.
Tenure
In February 2011, he made a joke in private meeting saying "I guess that if you are a Guatemalan gay man who likes to gamble and smokes marijuana, you probably think we're onto some good ideas here." In 2005, he sponsored legislation that would legalize medical marijuana. Watson has served as Minority Leader since elected by his caucus in November 1998. He ran for Speaker of the Rhode Island House of Representatives four times. The closest Watson ever got was when Republicans had 12 seats in the State House in 2003.
Committee assignments
During the 2009-2010 legislative session, Watson served on the Health, Education and Welfare Committee and the Joint Committee on Legislative Services. He served as the chairman of the East Greenwich Republican Town Committee from 1990 to 1992. He's also on the Commission on Judicial Tenure and Discipline.
Watson was stopped in East Haven, Connecticut at a police checkpoint on Friday, April 22, 2011. He was charged with possession of marijuana and drug paraphernalia after it was noted that a strong odor of marijuana was emanating from his car. He was also charged with driving under the influence. After further analysis of his urine by the Connecticut Toxicological Lab, Watson's blood alcohol content was determined to be.07, below the legal limit of.08. Traces of marijuana and cocaine were also found. On Jan 22, 2012 Robert Watson was arrested in South Kingston, RI for possession of marijuana and related paraphernalia. He was found to also have 3 open containers of alcohol in his possession. On November 6, 2017 Watson was arrested for attacking a bank and then breaking and entering into a neighbor's home. According to the police report he was naked and bleeding at the time.
