McQuillan made his 2011 debut at the Sony Open in Hawaii in Honolulu, the first PGA Tour event of his career. He survived the 36-hole cut with rounds of 68-69, then finishing on the 36-hole final day (caused by a rainout on the scheduled first round day) with 71-74 for 282 and 55th place, winning $12,705. McQuillan earned last-minute entry to the Bob Hope Classic in Palm Springs, shot a first-round 7-under-par 65 which included seven birdies and an eagle, but followed up with rounds of 76-73-77 to miss the fourth-round cut with a score of 3-over-par 291. At the Farmers Insurance Open in San Diego, McQuillan struggled with rounds of 74-77 to miss the halfway cut with a score of 7-over-par 151. McQuillan scored 76-76-68 for 6-over-par 220 in the AT&T National Pro-Am, missing the 54-hole cut. McQuillan shot rounds of 76-73 at the Mayakoba Golf Classic near Cancun, Mexico, missing the 36-hole cut. McQuillan scored 71-74 at the 2011 Puerto Rico Open, held just east of San Juan, Puerto Rico, to miss the 36-hole cut by one stroke.