Peter A. Reinberg (March 5, 1858 – February 21, 1921) was an American businessman and politician who was a very successful florist, and who served in the offices of president of the Cook County Board of Commissioners, president of the Chicago Board of Education, and Chicago alderman.

Reinberg was born on March 5, 1858, in Chicago, Illinois, where he was also raised. He born to Henry and Katherine Reinberg, immigrants who hailed from, Préizerdaul, Luxembourg. The family lived in the Edgewater neighborhood of Chicago, living near Rosehill Cemetery.

Reinberg was educated in Chicago Public Schools.

Reinberg had a very successful career as a florist. He had begun by growing turnips and potatoes, before experimenting with roses and flowers in 1890. He was very successful at growing roses and carnations, and eventually owned greenhouses with 1,200,000 square feet (110,000 square meters) of glass. He was among the most famous greenhouse owners in Chicago. He was considered the "Rose King" of Chicago. His business made him a millionaire, and he was among the largest rose growers in the world. He was also considered to be the largest grower of carnations in the United States.

Reinberg would serve on the board of directors of Ravenswood Bank.

In 1904, Reinberg made his political debut by successfully running as the Democratic nominee for Chicago City Council in the 26th district. In his campaign, he used the unique gimmick of providing each resident of his ward with carnations to wear.

Reinberg was reelected in 1906, 1908, and 1910. Reinberg was unseated in 1912 by Republican nominee George Pretzel.

In years such as 1908 and 1910, he had received election endorsements from the Municipal Voters League.