Urbanization in Indonesia increasingly unfolds outside formally designated cities, creating fast-growing urban territories that remain governed as regencies. This article examines Kudus Regency, Central Java, as a planning and management case of sustained non-city urbanization. Using longitudinal census and village-classification evidence for 1971–2020, district-level urbanization data for 1990, 2000, 2010, and 2020, and published qualitative evidence on infrastructure, industrial activity, and housing provision, the study develops a triangulated descriptive account of how demographic growth, village reclassification, and networked spatial expansion have produced a city-scale urban system within a regency framework. The results show a long-run increase in the urban population from 87,767 in 1971 to 788,240 in 2020, while the urbanization level rose from 19.53% to 92.82%. Between 1990 and 2020, the number of urbanized villages increased from 68 of 130 to 116 of 132. The main urban concentration grew from 233,017 to 375,495 inhabitants, while scattered urban concentrations expanded more sharply from 110,807 to 412,745 inhabitants, indicating that urban growth is no longer confined to the historic core. District evidence shows especially strong increases in Kaliwungu, Gebog, Jati, and Undaan, while Kecamatan Kota Kudus remained fully urbanized throughout the study period. Formal housing development remained spatially concentrated, with 38 housing complexes identified in total and 29 located in bordering districts, suggesting that informal and incremental settlement processes continue to absorb much of the regency’s urban growth. The findings position Kudus as a clear case of urban growth management under institutional lag: the territory functions as a city-scale urban system, yet it is still administered through a regency framework. The article contributes to management and planning research by documenting this administrative-spatial mismatch, clarifying the territorial pattern of growth, and showing why infrastructure sequencing, cross-district land-use coordination, and differentiated service planning are essential for urbanized regencies.