The 20-year-old woman had the baby at home some three to four weeks ago. She lives with the father of the child, the police spokesperson said.
"We have the impression that they both didn't want a baby," a police spokesman said at at press conference. An autopsy has shown the baby girl was alive at the time of birth, but it's not yet clear if she died from cold in the freezer or was asphyxiated.
Police arrested the woman, originally from Switzerland, under suspicion of manslaughter.
Germany has been plagued with gruesome infanticide cases in the last few years. One woman who killed nine of her babies was sentenced to 15 years in prison in early April.
Early this month, a 44-year-old woman was arrested when her family found three dead babies in her freezer near Bonn.
A 68-year-old pensioner in the neighbourhood where the mother lives in Horb said she was distraught over the news. "What's wrong with our country? Almost every two weeks there's something about new baby killings in the press. It's just completely out of hand," she said.