The Australians forced the playoff by shooting a 2-under 70 in alternate-shot play at the PGA Tour's lone regular-season team event. Oosthuizen and Schwartzel began the round with a one-stroke lead, but shot a 71 with three pars and two bogeys.
It's Smith's third career victory — second at the Zurich team event — and best result since tying for second at the pandemic-delayed 2020 Masters last November. It's also was his sixth top 10 since the current tour season started last October.
Smith's last victory came at the 2020 Sony Open in Hawaii.
It was Leishman's sixth career victory, his best result since tying for fifth at the Masters this month and his first win since the 2020 Farmers Insurance Open.