The publicly-listed British team released its 2013 financial results on Friday, showing a $20m operating profit despite a poor season on track.
The Telegraph newspaper said the result was helped by a one-off termination payment made by the Venezuelan oil company PDVSA, who wanted to move their backing of driver Maldonado to the Lotus team for 2014.
The report said the payment "is believed to be in the region of $25m", in the wake of a more than $8 million loss recorded by Williams just a year ago.
"We made good progress commercially through the winter months and Williams continues to attract an enthusiastic and very loyal group of partners and fans," team boss Sir Frank Williams said in Friday's statement.
"These annual results demonstrate that we continue to manage our business in a fiscally responsible way and provide the foundation from which we can continue to grow.
"We have started the 2014 formula one season well and hope we can continue to improve our performance," he added.