He worked as a stock clerk for a St. Paul, Minnesota wholesale hardware company before he took a position as a bookkeeper at the National German American Bank in 1887.

Bremer served as Treasurer of the City of St. Paul for over 10 years and was advisor to presidents Woodrow Wilson and Franklin D. Roosevelt.

He was subsequently appointed by Roosevelt to manage the Federal Home Owner's Loan Corporation of Minnesota.

In 1934, Edward Bremer, a banker and nephew of Otto, was kidnapped by the Karpis-Barker gang in broad daylight,[8] as he was dropping off his daughter at the Summit School in St. Paul.

This kidnapping, together with that of brewing heir William Hamm, Jr., brought an end to the O'Connor agreement, whereby St. Paul Police Chief John O'Connor allowed such gangsters to use St. Paul as a safe haven, provided they committed no crimes within the city.

With headquarters in St. Paul, Minnesota, the company is completely owned by employees and the Otto Bremer Trust.