District 3 Commissioner Randy Jones was reelected to a fourth-term without opposition.
Qualifying for the commission candidates ended noon on Friday.
Mahany, a lifelong Sanford resident, has served as the District 4 commissioner since June 2010 when a special election was held following the death of Commissioner Jack Bridges. Russi, who is also a lifelong Sanford resident, owns Toni Russi Insurance Agency in Sanford.
Commissioners serve a four-year term after elected and receive an annual salary of $7,500 plus $7,200 for expenses.
The election for the city commission will take place along with national and state elections on Nov.6.