Spain have been hit hard by the coronavirus, reporting more than 57,700 cases and 4,365 deaths.
The Madrid-born De Gea reportedly donated €300,000 to the Community of Madrid and Ayuso offered her thanks to the Spain international.
"Thank you, @D_DeGea!" she wrote on Twitter.
"The great help you have provided to @comunidadmadrid, it will be key to combat COVID-19.
"Eternally grateful, proud of you."
There have been more than 529,000 cases of coronavirus worldwide, with deaths nearing 24,000.
It has brought sport to a standstill, with De Gea's United fifth in the Premier League when it was suspended.