Last month, the British public voted to leave the European Union, which had a drastic effect on the economy in the United Kingdom, including their currency.
According to Bloomberg, Williams' prize money is worth $2.59 million - down from the pre-Brexit $2.97 million.
The 34-year-old will walk away with less than what she earned in 2015, despite the 6.4 percent hike up of prize money given this year.
Serena also won the doubles title along with her sister Venus and had £50 000 deducted from the original prize money.
According to Forbes, she is the highest paid female athlete with a net worth of $28.9 million.
Serena defeated Angelique Kerber 7-5, 6-3 to claim the Venus Rosewater Dish for the seventh time.