In his time as a senator, Sen. Williams has created legislation allowing those with sickle cell anemia to access needed pain medication prescriptions; protected individuals' MO ABLE funds for disability costs; and leads the Capitol's annual human trafficking awareness day.

During the 2021 legislative session, Sen. Williams passed comprehensive police reforms, Senate Bills 53 & 60, into law. These sweeping criminal justice reforms established the strongest use of force database in the country; prohibit law enforcement from using a respiratory chokehold without deadly force authorization; ensure women offenders have access to free, adequate feminine hygiene products while in a correctional facility or jail; and shortened the delay to request an expungement for those who have paid their debt to society. Senator Williams also added a provision that helps set innocent people free from wrongful imprisonment. This provision allows prosecutors and circuit attorneys to file a motion to vacate convictions if they believe the convicted person is innocent, a change that was instrumental in the 2021 release of Kevin Strickland, who was wrongfully convicted and served time for over 40 years.

During the 2022 legislative session, Sen. Williams proudly secured $98 million for North St. Louis County projects, including $40 million for the University of Missouri-St. Louis to construct the "Campus of the Future;" $15 million to manufacture active pharmaceutical ingredients; $23 million to build a public safety training facility; $7 million for public transit assistance; $6 million to abate, demolish and repurpose the Jamestown Mall; $4 million to renovate the St. Louis Metro Employment and Training Center in Wellston; and $400,000 for Youth Build Works.

In addition to legislative duties, Sen. Williams serves as a board director for People's Health Center, where he helped develop a behavioral health care center for underserved children. He is also a member of the advisory boards for St. Louis Crisis Nursery, Simmons Bank, iHeart Media, Nurses for Newborns, University City Children's Center, Alzheimer's Association and Refuge and Restoration.