Englishman Milkins takes home £230,000 in prize money after the tournament victory, the last Home Nations event of the year.
"It is unreal really. I had a lot of reasons to struggle. That is a lot of money," Milkins told Eurosport after his win.
"It is a life-changing sum of money. But the trophy is more important to me."
It is the second career title for the 46-year-old, who played out an enthralling final against his compatriot after the pair had gone in level at 4-4 after the afternoon session.
As both players made their share of unforced errors throughout, it was Milkins who repeatedly pulled away during the evening, with the Bristolian able to come through in an emotional fashion to triumph on the big stage at Venue Cymru.
For Murphy, it was so close and yet so far after reaching his first ranking final since finishing as runner-up to Mark Selby at the 2021 World Championships.
"I made far too many unforced errors. I couldn't have tried any harder," Murphy said.
"All credit to Rob, he was by far the better player. He fully deserved the victory."
