Mesuji Regency is a regency (kabupaten) of Lampung Province, on Sumatra island, Indonesia. It was created on 29 October 2008 from what were previously the most northern districts of Tulang Bawang Regency. It has an area of 2,200.51 km and a population of 187,286 people at the 2010 census and 227,518 at the 2020 census; the official estimate as at mid 2023 was 237,935 (comprising 122,391 males and 115,544 females). The regency seat is the town of Mesuji.

Administratively the regency is divided into seven districts (kecamatan), tabulated below with their areas and their populations at the 2010 census and 2020 census, together with the official estimates as at mid 2023. The table also includes the locations of the district administrative centres, the number of administrative villages in each district (all classed as rural desa), and its post code.

Kode Wilayah	Name of District (kecamatan)	Area in km	Pop'n 2010 census	Pop'n 2020 census	Pop'n mid 2023 estimate	Admin centre	No. of villages	Post code
18.11.04	Way Serdang	304.43	40,928	45,536	46,286	Bukoposo	20	34694
18.11.05	Simpang Pematang	166.38	23,175	28,995	30,679	Simpang Pematang	13	34699
18.11.06	Panca Jaya	96.27	15,355	18,633	19,466	Adi Luhur	7	34698
18.11.07	Tanjung Raya	357.00	33,949	43,428	46,069	Brabasan	21	34692
18.11.01	Mesuji	267.38	20,036	23,523	24,339	Wiralaga Mulya	11	34697
18.11.02	Mesuji Timur (East Mesuji)	617.78	29,751	39,896	42,905	Tanjung Mas Makmur	20	34695
18.11.03	Rawa Jitu Utara (North Rawa Jitu)	273.76	24,213	27,507	28,191	Panggung Jaya	13	34696
	Totals	2,184.00	187,407	227,518	237,935	Mesuji	105

In November 2010, four people were killed in a cock fight bust-up in the village of Wirabinangun.

4°02′38″S 105°24′05″E / 4.0439°S 105.4013°E / -4.0439; 105.4013