The oil firm will receive US$200mln in cash and it will also be able to release some US$75mln worth of letters of credit tied to future decommissioning liabilities for the field.
Premier said the deal generates proceeds that will accelerate the deleveraging of its balance sheet, with all the funds earmarked for debt repayment.
"The disposal will allow for a significant reduction in Premier's net debt and generates material value for shareholders,” said chief executive Tony Durrant.
“This is the latest in a series of disposals in line with Premier's strategy of realising value for shareholders at the appropriate stage of an asset's life cycle and at an attractive valuation."
Wytch Farm is estimated to have just shy of 15mln barrels of reserves and it contributed some 5,100 barrels oil equivalent production net to Premier Oil in the first six months of this year.