Rayner was born into a German-Jewish family[1] in Baltimore, Maryland, and attended local private schools.

In 1885, he was elected to the Maryland State Senate, serving one year until 1886.

Rayner was elected the same year to the 50th United States Congress.

Five years later in 1899, Rayner was chosen to be the Attorney General of Maryland, serving until 1903.

While senator, he served as chairman of the Committee on Indian Depredations (Sixty-second Congress).