[3] A former chess prodigy, So became the youngest player to pass a 2600 Elo rating in October 2008, breaking the record previously held by Carlsen.

In January 2007, So qualified for the Chess World Cup 2007 via the Zonal tournament held in Phú Quốc, Vietnam, scoring 5½/9.

In July 2008, So came second with 12½/17 in a tournament to decide the team for the 2008 38th Chess Olympiad, followed by sharing eighth place at the World Juniors Championship held in Gaziantep, Turkey.

He shared second with Zurab Azmaiparashvili scoring 6½/9 at the Vietnam Open but finished well back at the Arroyo Cup in sixteenth place.

So won a seat in the 2009 Chess World Cup by finishing second at the Zonal Championship held in July 2009 in Ho Chi Minh City, Vietnam.

[19] After competing in the Chinese Chess League, So shared fourth place at the SPICE Cup Group A with a solid 4½/10.

At the age of 16, So became one of the stories of the 2009 Chess World Cup held in Khanty-Mansiysk after progressing to the fourth round before being knocked out by Vladimir Malakhov after rapid tiebreaks.

So tied for fourth place at Tata Steel (formerly Corus) Group B but withdrew from the Aeroflot Open, held soon after, citing exhaustion from the previous event.

In September 2012, So found success in first place at the Quebec International, scoring 7½/9, half a point ahead of Lazaro Bruzon and at the 40th Chess Olympiad drew against numerous top-level players including Levon Aronian, who described So as a "talented player from a country with a great chess culture".

So also won gold at the 2013 Summer Universiade in Kazan, Russia, the first such medal for the Philippines, after a play off match with Zaven Andriasian.

[31] After defeating Alexander Ipatov in the first round of the Chess World Cup, he was knocked out by eventual semi-finalist Evgeny Tomashevsky.

[33] So tied for fourth with Fabiano Caruana and Leinier Domínguez Pérez at the 2014 Tata Steel Chess Tournament Group A, scoring 6/11.

[38] He also said that National Chess Federation of the Philippines (NCFP) disapproved of his participation in the 2013 Summer Universiade in Kazan, Russia over the 2013 Asian Indoor Games and he felt obliged to participate in tournaments deemed important by the NCFP such as the Southeast Asian Games over concern that he might lose financial support even if it conflicted with his studies in the United States.

[44] He won the Millionaire Chess Tournament held in Las Vegas in October 2014, scoring 8½/13 and shared second place at the Tata Steel Masters in January 2015.

[49] In December 2016, So also finished clear first at the 2016 London Chess Classic, ahead of former World Champions Viswanathan Anand, Vladimir Kramnik and Veselin Topalov.

Wesley So played for the Saint Louis Arch Bishops in the Professional Rapid Online Chess League competition, winning all four of his games two weeks in a row.

In week six, he and his team beat the division leader San Diego Surfers, which at the time had the only perfect record in the league.

[53] He had an undefeated streak of 67 games starting in July 2016, which ended in April 2017 after losing to the Azerbaijani GM Shakhriyar Mamedyarov who won the Shamkir Chess tournament.

[64][65] So had also won the semifinal match against Ian Nepomniachtchi by reaching a score of 13–5 in the third fast rapid game, posting 3 wins, 4 draws and again no losses.

Leonard Barden observed that the score unadjusted for time controls would be 5-1 and compared this "crushing" defeat to Bobby Fischer's double 6-0 victories in the 1971 Candidates.

[69][70] On October 1, 2020, the Saint Louis Arch Bishops were declared the winners of the 2020 Professional Rapid Online Chess League after the Armenia Eagles were disqualified due to fair play violations.

[72] On October 1, 2020, So accused Tigran L. Petrosian of cheating in his semi-final and final games during the Chess.com 2020 PRO Chess League (So was rated eighth-highest player in the world at the time).

[73][74] Chess.com determined that Petrosian had violated fair play regulations; consequently, his team, the Armenia Eagles, were disqualified and the Saint Louis Arch Bishops were crowned champions.

[78] On November 30, 2020, So defeated Carlsen to win the Skilling Open championship, the first leg of the Champions Chess Tour.

So then drew his classical match against Tabatabaei with one win and one loss but defeated him in rapid tiebreakers to face Hikaru Nakamura in the finals.

In November 2022 he won the first-ever Chess.com Global Championship for $200,000, defeating Hikaru Nakamura in the semi-finals and Nihal Sarin in the finals with a match score of 4.5-1.5.

As a young player, So's aggressive and tactical style of play caught the attention of a former Philippine chess champion, International Master Rodolfo Tan Cardoso.

Cardoso said of So: The young lad...would sacrifice a queen or any other pieces in his arsenal to get a winning attack....He cannot afford decent training given by well known GM-coaches and has to rely on his pure talent...before competing.

[84]His playing style has evolved in recent years to become more precise and risk-free, relying on taking advantage of opponent's mistakes.

[2] In the United States, So lives in Excelsior, Minnesota,[87] with Lotis Key, her husband Bambi Kabigting, and their daughter, whom he considers his adoptive family.