Johnson entered electoral politics again in 1986, when she was elected as a Texas state Senator. She was the first woman and the first African American from the Dallas area to hold this office since Reconstruction. Her particular concerns included health care, education, public housing, racial equity, economic development, and job expansion. Johnson served on the Finance Committee, for which she chaired the subcommittee on Health and Human Services, and on the Education Committee. She wrote legislation to regulate diagnostic radiology centers, require drug testing in hospitals, prohibit discrimination against AIDS victims, improve access to health care for AIDS patients, and prohibit hospital kickbacks to doctors. As a fair housing advocate, she sponsored a bill to empower city governments to repair substandard housing at the expense of landlords, and wrote a bill to enforce prohibitions against housing discrimination.