Arnoldi is a surname. Notable people with the surname include:
Bartholomaeus Arnoldi, an Augustinian friar associated with Martin Luther
Charles Arnoldi (born 1946), an American painter, sculptor and printmaker
Per Arnoldi (born 1941), a Danish designer and artist
Vladimir Arnoldi (1871-1924), a Russian writer of children's books and professor of biology
Walter Edwin Arnoldi (1917-1995), an American engineer known for the Arnoldi iteration
