| Singles | |
|---|---|
| 2018 Seoul Open Challenger | |
| Champion |  Mackenzie McDonald |
| Runner-up |  Jordan Thompson |
| Final score | 1–6, 6–4, 6–1 |
Thomas Fabbiano was the defending champion but chose not to defend his title.
Mackenzie McDonald won the title after defeating Jordan Thompson 1–6, 6–4, 6–1 in the final.
Vasek Pospisil (second round)
Dudi Sela (first round) Jordan Thompson (final)
Lu Yen-hsun (second round, retired) Mackenzie McDonald (champion)
Go Soeda (second round) Jason Jung (second round) Tatsuma Ito (semifinals)| Semifinals | Final | ||||||||||||
| Jason Kubler | 3 | 6 | 4 | ||||||||||
| 3 | Jordan Thompson | 6 | 3 | 6 | |||||||||
| 3 | Jordan Thompson | 6 | 4 | 1 | |||||||||
| 5 | Mackenzie McDonald | 1 | 6 | 6 | |||||||||
| 5 | Mackenzie McDonald | 6 | 77 | ||||||||||
| 8 | Tatsuma Ito | 4 | 64 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | V Pospisil | 4 | 6 | 6 | |||||||||||||||||||||||
| B Schnur | 6 | 1 | 3 | 1 | V Pospisil | 3 | 3 | ||||||||||||||||||||
| J Kubler | 6 | 6 | J Kubler | 6 | 6 | ||||||||||||||||||||||
 Ze Zhang | 1 | 1 | J Kubler | 6 | 6 | ||||||||||||||||||||||
 S-w Kwon | 6 | 1 | 6 | S-w Kwon | 3 | 4 | |||||||||||||||||||||
 M Janvier | 1 | 6 | 3 | S-w Kwon | 6 | 6 | |||||||||||||||||||||
| M Giron | 6 | 3 | 4 | 6 | G Soeda | 4 | 4 | ||||||||||||||||||||
| 6 | G Soeda | 1 | 6 | 6 | J Kubler | 3 | 6 | 4 | |||||||||||||||||||
| 3 | J Thompson | 6 | 6 | 3 | J Thompson | 6 | 3 | 6 | |||||||||||||||||||
| WC | Kim Young-seok | 1 | 2 | 3 | J Thompson | 7 | 711 | ||||||||||||||||||||
| F Peliwo | 7 | 3 | 1r | Q | J-h Son | 5 | 69 | ||||||||||||||||||||
| Q | Son Ji-hoon | 5 | 6 | 3 | 3 | J Thompson | 6 | 6 | |||||||||||||||||||
| Q | Renta Tokuda | 1 | 2 | T-h Yang | 1 | 3 | |||||||||||||||||||||
| T-h Yang | 6 | 6 | T-h Yang | 6 | 7 | ||||||||||||||||||||||
| Q | Makoto Ochi | 4 | 0 | 7 | J Jung | 4 | 5 | ||||||||||||||||||||
| 7 | J Jung | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 5 | M McDonald | 7 | 6 | ||||||||||||||||||||||||
| WC | U-s Park | 5 | 2 | 5 | M McDonald | 6 | 6 | ||||||||||||||||||||
| SE |  K Majchrzak | 6 | 6 | SE | K Majchrzak | 3 | 4 | ||||||||||||||||||||
| Y Takahashi | 2 | 3 | 5 | M McDonald | 64 | 710 | 6 | ||||||||||||||||||||
 L Harris | 5 | 6 | 6 | L Harris | 77 | 68 | 3 | ||||||||||||||||||||
| WC | Y-s Chung | 7 | 3 | 0 | L Harris | 6 | 3 | ||||||||||||||||||||
| M Banes | 4 | 1 | 4 | Y-h Lu | 4 | 0r | |||||||||||||||||||||
| 4 | Y-h Lu | 6 | 6 | 5 | M McDonald | 6 | 77 | ||||||||||||||||||||
| 8 | T Ito | 6 | 6 | 8 | T Ito | 4 | 64 | ||||||||||||||||||||
| D-h Lee | 1 | 3 | 8 | T Ito | 7 | 6 | |||||||||||||||||||||
| Y Uchiyama | 6 | 4 | 5 | WC | S-c Hong | 5 | 1 | ||||||||||||||||||||
| WC | S-c Hong | 2 | 6 | 7 | 8 | T Ito | 7 | 3 | 6 | ||||||||||||||||||
| Q | Yo Watanuki | 6 | 6 | D Wu | 5 | 6 | 2 | ||||||||||||||||||||
| D Kelly | 3 | 4 | Q | Yo Watanuki | 4 | 5 | |||||||||||||||||||||
| D Wu | 6 | 2 | 6 | D Wu | 6 | 7 | |||||||||||||||||||||
| 2 | D Sela | 3 | 6 | 0 | |||||||||||||||||||||||
George Morgan and Mate Pavić were the defending champions but were no longer eligible to compete as Juniors.
Robin Kern and Julian Lenz were the defending champions, having won the event in 2011.
Kyle Edmund and Frederico Ferreira Silva won the title, defeating Nick Kyrgios and Jordan Thompson 6–2, 2–6, 7–5 in the final.
James McGee was the defending champion but chose not to defend his title.
Roger Federer defeated Rafael Nadal in the final, 6–4, 6–3 to win his second title in Shanghai. It was his 27th Masters 1000 title.
Ryan Harrison was the defending champion but chose not to defend his title.
Sam Querrey was the defending champion, but lost in the first round to Matthew Ebden.
Thomas Fabbiano was the defending champion but chose not to defend his title.
Yūichi Sugita was the defending champion but chose not to defend his title.
Gilles Müller was the defending champion, but lost in the second round to Matthew Ebden.
Novak Djokovic defeated Borna Ćorić in the final, 6–3, 6–4 to win the singles title at the 2018 Shanghai Masters. It was his record fourth Shanghai Masters title, and 32nd Masters 1000 title overall.
Mackenzie McDonald was the defending champion but chose not to defend his title.
Roberto Bautista Agut was the defending champion, but withdrew before the tournament began.
Kei Nishikori was the defending champion but chose not to defend his title.
Steve Johnson was the two-time defending champion, but lost in the second round to Daniel Elahi Galán.
Mackenzie McDonald was the defending champion but chose not to defend his title.
Reilly Opelka was the defending champion, but lost to Jason Jung in the quarterfinals.
Novak Djokovic defeated Milos Raonic in the final, 1–6, 6–3, 6–4, to win the men's singles title at the 2020 Cincinnati Masters. With the win, he claimed his record-equaling 35th ATP Masters 1000 title, and completed the career Golden Masters for a second time. Djokovic became the first new singles titlist on the ATP Tour since its suspension due to the COVID-19 pandemic in March 2020.
Ivan Dodig and Filip Polášek defeated defending champions Rajeev Ram and Joe Salisbury in the final, 6–3, 6–4, to win the men's doubles tennis title at the 2021 Australian Open. By winning the title, Dodig and Polášek won their first Grand Slam doubles title as a team. The victory also earned Polášek his first major title and made him the second Slovak player to win one after compatriot Daniela Hantuchová.
Alexander Zverev was the defending champion from when the event was held in 2019, but chose not to defend his title.
Diego Schwartzman was the reigning champion from when the tournament was last held in 2019, but chose to compete at the Summer Olympics instead.