Lehnert is a German surname. Notable people with the surname include:
- Adolf Lehnert (1862–1948), German sculptor and medal designer
- Andreas Lehnert, German clarinetist
- Jürgen Lehnert (born 1954), East German sprint canoeist
- Katharina Lehnert (born 1994), Filipino-German tennis player
- Michael R. Lehnert, retired major general of the United States Marine Corps
- Pascalina Lehnert (1894–1983), German Roman Catholic sister
- Rudolf Franz Lehnert, photographer
- Wendy Lehnert, American computer scientist