On 22 January 2020, during the first test against Zimbabwe, Mathews scored his maiden double hundred. He scored unbeaten 200 runs in 465 balls within 600 minutes in the middle. His double hundred is recorded as the first double hundred scored by a Sri Lanka in five years after Sangakkara's double in 2015. Finally Sri Lanka won the match by 10 wickets and Mathews won the man of the match award. Sri Lanka was able to draw the second Test due to second innings unbeaten century by Kusal Mendis and sealed the series 1-0. Mathews won the player of the series award becoming highest run scorer in the series. Mathews scored 277 runs with a double hundred and one fifty at an average 138.50.