Swimming at the 2023 World Aquatics Championships – Men's 400 metre freestyle

Prior to the competition, the existing world and championship records were as follows.^[4]

World record	Paul Biedermann (GER)	3:40.07	Rome, Italy	26 July 2009
Competition record	Paul Biedermann (GER)	3:40.07	Rome, Italy	26 July 2009

Heats

The heats were started at 10:47.^[5]

Rank	Heat	Lane	Name	Nationality	Time	Notes
1	6	4	Samuel Short	Australia	3:42.44	Q
2	6	3	Felix Auböck	Austria	3:44.14	Q
3	5	5	Guilherme Costa	Brazil	3:44.17	Q
4	5	7	Ahmed Hafnaoui	Tunisia	3:44.34	Q
5	5	4	Lukas Märtens	Germany	3:44.42	Q
6	6	2	Kim Woo-min	South Korea	3:44.52	Q
7	6	5	Elijah Winnington	Australia	3:44.63	Q
8	5	3	Antonio Djakovic	Switzerland	3:45.43	Q
9	5	2	Kieran Smith	United States	3:45.77
10	6	0	Kristóf Rasovszky	Hungary	3:46.56
11	5	0	Alfonso Mestre	Venezuela	3:46.61	NR
12	6	6	Marco De Tullio	Italy	3:47.23
13	5	1	Lucas Henveaux	Belgium	3:47.88
14	6	1	Matteo Ciampi	Italy	3:48.12
15	5	8	Marwan Elkamash	Egypt	3:48.31
16	4	7	Kregor Zirk	Estonia	3:48.43
17	6	7	David Johnston	United States	3:48.68
18	4	5	Bar Soloveychik	Israel	3:49.21
19	4	2	Dimitrios Markos	Greece	3:49.41
20	4	1	Carlos Quijada	Spain	3:49.60
21	5	6	Oliver Klemet	Germany	3:49.79
22	4	6	Krzysztof Chmielewski	Poland	3:49.90
23	4	8	Eric Brown	Canada	3:50.68
24	4	3	Khiew Hoe Yean	Malaysia	3:50.78
25	6	8	Logan Fontaine	France	3:51.56
26	4	4	Luke Turley	Great Britain	3:51.95
27	4	0	Jovan Lekić	Bosnia and Herzegovina	3:53.17
28	3	6	Joaquín Vargas	Peru	3:53.54
29	3	2	Eduardo Cisternas	Chile	3:53.80	NR
30	3	5	Velimir Stjepanović	Serbia	3:54.25
31	4	9	Glen Lim Jun Wei	Singapore	3:54.42
32	6	9	Zac Reid	New Zealand	3:55.55
33	5	9	Zhang Ziyang	China	3:55.76
34	3	1	Tonnam Kanteemool	Thailand	3:56.69
35	3	3	Kushagra Rawat	India	3:59.03
36	3	4	Đỗ Ngọc Vĩnh	Vietnam	4:02.05
37	3	7	Pavel Alovatki	Moldova	4:02.43
38	3	0	Loris Bianchi	San Marino	4:03.88
39	2	3	Sauod Al-Shamroukh	Kuwait	4:04.95
40	2	8	Gerald Hernández	Nicaragua	4:05.13	NR
41	2	4	Alberto Vega	Costa Rica	4:05.18
42	1	6	Raekwon Noel	Guyana	4:05.70
43	2	5	Théo Druenne	Monaco	4:06.58	NR
44	1	4	Mal Gashi	Kosovo	4:07.65
45	2	6	Nikola Gjuretanovikj	North Macedonia	4:07.87
46	2	0	Nasir Yahya Hussain	Nepal	4:08.23	NR
47	2	7	Líggjas Joensen	Faroe Islands	4:09.17
48	2	9	Timothy Leberl	Mauritius	4:09.47
49	2	1	Mauricio Arias	Dominican Republic	4:11.15
50	1	5	Muhammad Siddiqui	Pakistan	4:12.29	NR
51	2	2	José Campo	El Salvador	4:15.97
52	3	9	Dylan Cachia	Malta	4:16.27
53	1	2	Ali Al-Awi	Bahrain	4:17.02	NR
54	1	3	Mohammed Al-Zaki	Saudi Arabia	4:20.48
55	3	8	Mark Ducaj	Albania	4:20.88

Final

The final was started at 20:02.^[6]

Rank	Lane	Name	Nationality	Time	Notes
	4	Samuel Short	Australia	3:40.68
	6	Ahmed Hafnaoui	Tunisia	3:40.70	AF
	2	Lukas Märtens	Germany	3:42.20
4	3	Guilherme Costa	Brazil	3:43.58
5	7	Kim Woo-min	South Korea	3:43.92
6	8	Antonio Djakovic	Switzerland	3:44.22
7	1	Elijah Winnington	Australia	3:44.26
8	5	Felix Auböck	Austria	3:44.43