Twenty teams qualified and each named an initial squad of 33 players, two more than at the previous World Cup.
[2] 1 On 10 September 2023, Emoni Narawa was ruled out of the World Cup, after sustaining a back injury.
[9] 1 On 6 September 2023, Chad Plato was ruled out of the World Cup, after sustaining a thigh injury.
[10] 2 On 17 September 2023, Le Roux Malan was ruled out of the World Cup, after sustaining an ankle injury.
[12] 1 On 14 September 2023, Malcolm Marx was ruled out of the World Cup, after sustaining a knee injury.
[14] 2 On 2 October 2023, Makazole Mapimpi was ruled out of the World Cup, after sustaining a fractured eye socket.
[21] 1 On 18 September 2023, Feao Fotuaika and Otumaka Mausia were ruled out of the World Cup, after sustaining various injuries.
[22] 2 On 29 September 2023, Siua Maile and Solomone Funaki were ruled out of the World Cup, after sustaining various injuries.
[25] 2 On 19 September 2023, Romania replaced Gabriel Pop, Taylor Gontineac and Hinckley Vaovasa with Luca Nichitean, Mihai Graure and Alexandru Bucur because of various injuries.
[32] 1 On 1 September 2023, Caleb Muntz was ruled out of the World Cup, after sustaining a knee injury.
[37] 1 On 27 September 2023, Beka Gorgadze was ruled out of the World Cup, after sustaining an ankle injury.
[38] 2 On 2 October 2023, Tengiz Zamtaradze, Mirian Modebadze and Lasha Jaiani were ruled out of the World Cup, after sustaining various injuries.
[41] 1 On 14 August 2023, Jack van Poortvliet was ruled out of the World Cup, after sustaining an ankle injury.
[46] Head coach: Steve Borthwick On 15 August 2023, Japan named an initial 30-player squad for the World Cup, with three players remaining to be added.
[47] On 18 August 2023, Warner Dearns, Amanaki Saumaki and Lappies Labuschagné were added to complete the 33-player squad.
[48] 2 On 29 August 2023, Uwe Helu and Shōgo Nakano were withdrawn due to performance issues and replaced by Amato Fakatava and Kanji Shimokawa.
[55] 1 On 18 September 2023, Luteru Tolai was ruled out of the World Cup, after sustaining a knee injury.