Bing was seen entering City Hall at 8 a.m., The Detroit News reported.
The mayor had been out of office since March 22 when he was hospitalized for colon surgery. After being released from the hospital following the surgery, he was readmitted and diagnosed with acute pulmonary embolism.
Bing made his first public appearance since his surgery Sunday at Comerica Park for Walk MS Detroit.
He was joined by his wife Yvette at the walk, which was aimed at raising awareness and funding for multiple sclerosis research.
In a recent phone call with reporters, Bing said he had been participating in the process of hiring a chief financial officer as well as appointing members to Detroit's financial advisory board. He also said he will likely not work full days until his health is 100 percent.