Walwyn made his first-class debut for the Leeward Islands against Barbados in the 1993/94 Red Stripe Bowl.
He made six further first-class appearances for the team, the last of which came against Jamaica in the 1994/95 Red Stripe Bowl.
[3] He also played List A cricket for the Leeward Islands, making his debut in that format against Barbados in the 1993/94 Geddes Grant Shield.
He made five further List A appearances for the team, the last of which came against Barbados in the final of the same tournament, which the Leeward Islands won.
[5] In February 2006, Walwyn played for the United States Virgin Islands in the 2006 Stanford 20/20, whose matches held official Twenty20 status.