McAleer was introduced to motorsport at the age of ten at a karting track in Glasgow, and received a go-kart as a gift from his father at eleven. After winning the Scottish Karting Championship four times, he moved to the United States in 2005 to pursue racing opportunities, gaining entry to the Skip Barber Regional Championship through a scholarship he discovered in Autosport. In his first season in the Eastern Regional Championship he finished second in points, recording seven wins and fourteen podiums. He subsequently competed in the Skip Barber National Championship for several seasons, funding his career partly by working at a supermarket and a karting facility in New York.
McAleer entered the 2012 Global MX-5 Cup after contact made at the 25 Hours of Thunderhill connected him with MLB pitcher and team owner C. J. Wilson. He won the opening weekend at Sebring, claimed two additional victories, and secured the series championship. The prize gave him a full season in the Continental Tire Sports Car Challenge, where he teamed with Marc Miller for C.J. Wilson Racing and won class races at COTA and Watkins Glen, earning the series Rookie of the Year award.
Paired with Chad McCumbee from 2014 onwards, McAleer developed one of the most effective co-driver partnerships in the Street Tuner class. After several years of podiums and individual victories, the duo entered the decisive final race of the 2015 season at Road Atlanta leading the championship by a single point. They finished eighth in class but held on to claim the Street Tuner title. The following season they moved to Freedom Autosport, adding victories at Laguna Seca and Lime Rock and finishing fourth in the championship.
McAleer expanded his programme steadily through the late 2010s, competing across the Continental Tire SportsCar Challenge, Pirelli World Challenge, and Lamborghini Super Trofeo North America in 2018. His most productive period came from 2019 onwards. In the IMSA Prototype Challenge in 2019, he claimed his first solo victory in the series at Sebring and finished second in the championship. He simultaneously competed in the GT4 America Series with Classic BMW alongside Justin Raphael, taking two victories and the East Pro-Am Cup title.
In 2021, McAleer and Toby Grahovec finished fourth in the GT4 America Silver Cup championship, while his Michelin Pilot Challenge partnership with Patrick Gallagher at RS1 produced an overall race victory at Watkins Glen.
The 2022 season brought his most comprehensive success. Competing full-time in the GT4 America Silver Cup alongside Eric Filgueiras for RS1, the pair claimed eleven class victories from fourteen races, sweeping four of the seven championship weekends at Sonoma, NOLA, Watkins Glen, and Indianapolis to clinch the title with a race in hand. McAleer also competed full-time in the IMSA SportsCar Championship in the GTD class for Team Korthoff Motorsports alongside Mike Skeen, finishing third in the standings despite no race victories.
In 2023, McAleer and Filgueiras moved their partnership to the GT World Challenge America with RS1 in the Pro class, winning the opening race at Sonoma, adding an overall victory at NOLA and a class win at COTA, and claiming the Pro class championship by 44 points over Mario Farnbacher and Ashton Harrison.
In 2015, McAleer and Chad McCumbee established their own team, McCumbee McAleer Racing, to compete in the Mazda MX-5 Cup series. Based in Supply, North Carolina, the team launched with three cars under ModSpace title sponsorship and won two races in its debut season, earning the Team of the Year award. Driver Patrick Gallagher, competing for the team in 2017, claimed the MX-5 Cup series championship with eight victories and was again recognized with the Team of the Year accolade. In 2018 the team received the Clean Image Award for paddock presentation. In 2023 the team expanded to GT4 competition, fielding a Ford Mustang GT4 in the Michelin Pilot Challenge for McCumbee and former MX-5 Cup driver Jenson Altzman.
Throughout his competitive career McAleer has worked as a professional driver coach, a role he traces to his time working at a karting facility in Mount Kisco, New York, where he met Monticello Motor Club president Ari Straus. He views coaching as a complementary discipline that strengthens his own racecraft. In 2022 he also served as a judge for Mazda Motorsports' Spec MX-5 shootout competition.
McAleer's record across more than a decade of North American sports car racing — multiple class titles, a co-owned team that has produced series champions, and a parallel coaching career — marks him as one of the most substantive British exports to the American GT scene. His longevity and adaptability across manufacturers, classes, and series formats set him apart from many of his contemporaries.