Tonya began her legal career working as Millender Fellow (in honor of the late Robert L. Millender) at the historic Sugar Law Center for Economic and Social Justice. While at Sugar Law, she worked to strengthen the investigatory and enforcement provisions of the Detroit Living Wage Ordinance, which mandated workers be paid a "living wage" for their services on high-value city contracts. She also worked on litigation on behalf of Detroit Public Schools students to force the district to remediate a school that had been built on an environmentally contaminated site.

After working at the Sugar Law Center, Tonya entered private practice, where she helped small business owners and nonprofit organizations all across the city. She also began teaching a "How to Become a Nonprofit" mini-course, free of charge to the community, in conjunction with the Detroit Association of Black Organizations.

Tonya returned to the Sugar Law Center in 2019 and serves as the Director of Community Partnerships & Development where she advocates for community benefits agreement and equitable development policies. She serves as a Public Policy Advisor with Michigan Legal Services and leads an initiative to provide a right to legal counsel for low-income tenants facing eviction in Detroit.

Tonya served as a member of the City of Detroit Charter Revision Commission, where she frequently advocated for increased citizen participation in government. She currently serves on the board of the National Lawyers Guild-Detroit Chapter and Sidewalk Festival Detroit.

Mrs. Phillips has been recognized for her leadership and community service. She is the recipient of distinguished awards such as "Distinguished Young Lawyer Award" from the Wolverine Bar Association, and the "Maryann Mahaffey Public Servant of the Year Award" from the United Community Housing Coalition.