Muhlenberg was a member of the Muhlenberg Family political dynasty. He was born in Reading, Pennsylvania on July 21, 1823. His father, Henry A. P. Muhlenberg, was a Congressman and U.S. Minister to Austria; his grandfather, Joseph Hiester, was the governor of Pennsylvania.
Muhlenberg attended Dickinson College in Carlisle, Pennsylvania. He studied law and was admitted to the bar in 1844, practicing law in Reading, Pennsylvania. He was elected to the Pennsylvania State Senate in 1849, serving until 1852 when he was elected to the United States House of Representatives to represent the 8th Congressional district. He began Congressional service on March 4, 1853, and died less than a year later.
His son, Henry Augustus Muhlenberg, III ran for Congress in 1892, unsuccessfully.