The 26-year-old butcher was convicted by a jury at Sheffield Crown Court on Thursday.
The married-father-of-two was convicted by a majority verdict.
The 21-year-old's body was recovered from the Humber Estuary in March, nearly two months after she went missing.
Libby Squire went missing after a night out with friends in Hull.
Young woman's body was recovered from the Humber Estuary six weeks after she disappeared in February.
"I kept you safe for as long as I could and I am so sorry I could not keep you safe on that night. I’m sorry," Lisa Squire wrote.
"We are all absolutely devastated by the loss."
Pawel Relowicz is facing a dozen charges of burglary, voyeurism, and outraging public decency.
He remains under investigation in relation to the disappearance of the university student.
He was remanded in custody.