Trotman has made just three first-team appearances for North End, having joined from Oldham in January 2008, and finished last season on loan at Colchester.
However, Trotman has decided to stay and fight for his place at Preston, despite not making the squad for the opening day visit of Bristol City.
Boss Alan Irvine told the Lancashire Evening Post: "There was an enquiry from Millwall asking about taking Trots on loan, I spoke to him about it, and he told me he wanted to stay here and fight for a place in our team which is great.
"We have got four centre-backs who are all fit at the moment, and the reason Trots wasn't on the bench on Saturday was that I didn't need two centre-backs as substitutes.
"He won't always miss out. His fitness is fine now and he got through pre-season without any problems."