| Date | 21 – 24 August 1920 | |
|---|---|---|
| Status | Olympic | |
| Location | Feestzaal, Koninklijke Zoölogische Maatschappij, Antwerpen | |
| Participants | 16 from 9 countries | |
| Format | Single elimination tournament. | |
The flyweight division was won by Frankie Genaro, who was born Frank DiGennara. Shortly after the Olympics, he turned professional and became World professional flyweight champion for several years. In the finals, he won by a unanimous decision over Anders Petersen of Denmark.
| Pos | Number | Competitor | NOC | |||
|---|---|---|---|---|---|---|
| 1 | 2 | Frankie Genaro |  USA | Gold | ||
| 2 | 12 | Anders Petersen |  DEN | Silver | ||
| 3 | 4 | William Cuthbertson |  GBR | Bronze | ||
| 4 | 15 | Charles Albert |  FRA | |||
| =5 | 7 | Jef Charpentier |  BEL | |||
| =5 | 14 | Jean-Baptiste Rampignon | FRA | |||
| =5 | 18 | Ted Zegwaard |  NED | |||
| =5 | 1 | Pete Zivic | USA | |||
| =9 | 20 | Einar Nilsen |  NOR | |||
| =9 | 10 | Harry Turner |  CAN | |||
| =9 | 21 | Peder Kjellberg | NOR | |||
| =9 | 164 | Pietro Dell'Oro |  ITA | |||
| =9 | 11 | Einer Jensen | DEN | |||
| =9 | 5 | Frederick Virtue | GBR | |||
| =9 | 17 | Nelis van Dijk | NED | |||
| =9 | 8 | Androt | BEL |
| Date | 21 August 1920 |
|---|---|
| Format | Winner of each match advanced to the second round. |
| Match | Date/Time | Competitor | NOC | Result | Competitor | NOC | |
|---|---|---|---|---|---|---|---|
| Match #1 | 21 Aug | Frankie Genaro | USA | Decision | Einar Nilsen | NOR | |
| Match #2 | 21 Aug | Jean-Baptiste Rampignon | FRA | Knock-out | Harry Turner | CAN | |
| Match #3 | 21 Aug | Jef Charpentier | BEL | Decision | Peder Kjellberg | NOR | |
| Match #4 | 21 Aug | Charles Albert | FRA | Referee stops contest | Pietro Dell'Oro | ITA | |
| Match #5 | 21 Aug | William Cuthbertson | GBR | Decision | Einer Jensen | DEN | |
| Match #6 | 21 Aug | Ted Zegwaard | NED | Decision | Frederick Virtue | GBR | |
| Match #7 | 21 Aug | Anders Petersen | DEN | Decision | Nelis van Dijk | NED | |
| Match #8 | 21 Aug | Pete Zivic | USA | Decision | Androt | BEL |
| Date | 22 August 1920 |
|---|---|
| Format | Winner of each match advanced to the semi-finals. |
| Match | Date/Time | Competitor | NOC | Result | Competitor | NOC | |
|---|---|---|---|---|---|---|---|
| Match #1 | 22 Aug | Frankie Genaro | USA | Decision | Jean-Baptiste Rampignon | FRA | |
| Match #2 | 22 Aug | Charles Albert | FRA | Referee stops contest | Jef Charpentier | BEL | |
| Match #3 | 22 Aug | William Cuthbertson | GBR | Decision | Ted Zegwaard | NED | |
| Match #4 | 22 Aug | Anders Petersen | DEN | Decision | Pete Zivic | USA |
| Date | 23 August 1920 |
|---|---|
| Format | Winner of each match advanced to the final match. |
| Match | Date/Time | Competitor | NOC | Result | Competitor | NOC | |
|---|---|---|---|---|---|---|---|
| Match #1 | 23 Aug | Frankie Genaro | USA | Decision | Charles Albert | FRA | |
| Match #2 | 23 Aug | Anders Petersen | DEN | Decision | William Cuthbertson | GBR |
| Date | 24 August 1920 |
|---|
| Match | Date/Time | Competitor | NOC | Result | Competitor | NOC | |
|---|---|---|---|---|---|---|---|
| Match 1/2 | 24 Aug | Frankie Genaro | USA | Decision | Anders Petersen | DEN | |
| Match 3/4 | 24 Aug | William Cuthbertson | GBR | Decision | Charles Albert | FRA |
