Peter Langkjær Madsen is born in Kalundborg, Denmark. His early childhood is reportedly marked by a challenging relationship with his father.

Growing up, Madsen displays a keen interest in science, technology, and particularly space exploration. He spends much of his time building models and conducting amateur experiments. Some reports suggest he struggled socially.

Madsen attends a technical school, focusing on engineering and related subjects. Details about his formal education are somewhat fragmented, but it's evident that he possessed a strong practical understanding of mechanics and engineering principles, gained through both formal education and self-study. He is reportedly not a graduate, as he dropped out of his formal technical education.