Elected to the Arkansas Senate in 1950 to represent part of Pulaski County, he would go on to hold the office for forty-two years. He held leadership positions on more than 20 committees throughout his career including Legislative Council, Senate Budget Committee, Judiciary Committee, Select Committee on Children and Youth, Communications Study Commission, Joint Performance and Review Committee, and Administrative Rules and Regulations Committee.
His most celebrated legislation included the development of a modern mental health system in Arkansas, the merger of Little Rock University (now University of Arkansas at Little Rock) with the University of Arkansas System, the establishment of the UA Little Rock Law School, creation of an adult probation system for the state, and assistance in saving the Old State House in Little Rock from demolition.
He also worked to consolidate school districts and allocate more funding to the Pulaski County Special School District. Howell was responsible for the establishment of 23 vocational-technical schools and sought improvement in child custody, adoption, and abuse issues, as well as juvenile court. In addition, his work with the Department of Human Services led to the creation of the Department of Natural and Cultural Heritage and the Little Rock Convention Center.
Howell retired from the Senate in 1992 after the adoption of constitutional amendment 73 limiting the terms of legislators.