Piercy started by playing on various mini-tours. In 2007, Piercy won the Ultimate Game at Wynn Las Vegas G&CC, earning $2 million. Piercy became a Nationwide Tour member in 2008. After a poor start to the season, he won two tournaments in August and finished ninth on the money list to earn PGA Tour playing rights for 2009. Piercy made an encouraging start to his PGA Tour career, recording five top-twenty finishes in his first six starts, and this run of form elevated Piercy into the top 100 of the Official World Golf Rankings in March 2009. He finished the season ranked 90th on the money list to retain his tour card, but slipped to 136th in 2010, and lost some of his tour status for 2011. In 2011, Piercy won his first PGA Tour event at the Reno-Tahoe Open, an alternate event in early August. His second tour win came in July 2012 at the RBC Canadian Open, one stroke over runners-up Robert Garrigus and William McGirt. As a result, Piercy earned a place in the following week's WGC-Bridgestone Invitational and was therefore unable to defend his Reno-Tahoe Open title. In early November, he was a runner-up at the WGC-HSBC Champions in China. The Canadian Open win gained Piercy entry into the Masters in 2013, his first, and made the cut. During the 2013 season, he finished third at the Waste Management Phoenix Open, tied for fifth at the PGA Championship and Byron Nelson Championship, and reached the round of 16 at the WGC-Accenture Match Play Championship. In the 2014 season, Piercy had an arm injury and was out for five months. In his return, he had a best result of T-12 at the Wyndham Championship. In the 2015 season, he finished seventh at the Shriners Hospitals for Children Open, runner-up at the Sony Open in Hawaii, tenth at the Shell Houston Open. In July, he won the inaugural Barbasol Championship in Alabama, an alternate event opposite the Open Championship, for his first victory in three years. Piercy was unable to defend his title in 2016 because he earned entry into the 2016 Open Championship. In March 2020, Piercy shared a meme on his Instagram page of Pepe the Frog and Pete Buttigieg which stated "Peter pulls out early from behind." The post was considered homophobic by Queerty and ESPN, which both reported Piercy is losing multiple sponsorships, including Titleist, FootJoy, and J.Lindeberg, totaling over $2 million in lost sponshorships. Additionally, the PGA Tour stated "We were made aware of Scott's post and are disappointed in the lack of judgment used."
