At the time of the organization of the township the citizens wanted to call it Cambria; however, since there was already a township by that name in Michigan, their Representative at that time, Judge Littlejohn of Allegan, proposed they name it after Roman Emperor Flavius Marcellus.

As a result, on June 16, 1843, the township was officially named Marcellus.

In the winter of 1870–71 the Peninsular Railroad came through Marcellus, infusing life into the small township.

After this move, business began rapidly expanding and an addition was added to the station to meet the increased traffic demands.

Three years later it had grown and included 2 churches, 3 dry goods stores, 3 groceries, 3 millinery shops, 2 drug stores, 2 meat markets, 2 hotels, 2 tin shops, a bank, 2 stave factories, 2 harness shops, a hardware store, a furniture store, a restaurant, a printing business, a tailor shop, a cooper shop, a steam saw mill, a sash and blind manufacturer, 4 doctors, 2 lawyers, 2 justices of the peace, and a newspaper.

During its height, Marcellus was also home to two theaters, a bowling alley, and a pool hall.

Each year it hosts the National Bluegill Frolic, and previously hosted a parade, fishing tournament, and beauty pageant which attracted thousands each year.

20.4% of all households were made up of individuals, and 9.6% had someone living alone who was 65 years of age or older.

22.7% of all households were made up of individuals, and 11.4% had someone living alone who was 65 years of age or older.