約翰遜縣 (密蘇里州)

{{Infobox U.S. county
| state = Missouri
| county = Johnson County
| county_zh = 約翰遜縣
| seal =
| seal size =
| ex image =
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| founded =
| named for = Former Vice President Richard M. Johnson
| seat =
| largest city =
| largest city wl = Warrensburg
| area_total_km2 = 2,158
| area_total_sq_mi = 833
| area_land_km2 = 2,151
| area_land_sq_mi = 830
| area_water_km2 = 7
| area_water_sq_mi = 3
| area percentage = 0.31%
| census yr = 2000
| census estimate yr =
| pop = 48,258
| population_density_km2 = 22
| population_density_sq_mi = 58
| time zone = Central
| web =
| coordinates = {{coord|{}|0|N|{}|0|W|type:adm2nd|display=title,inline}}
}}
約翰遜縣（）是美國密蘇里州西部的一個縣。面積2,158平方公里。根據美國2000年人口普查，共有人口48,258人。縣治沃倫斯堡 (Warrensburg)。

成立於1834年12月13日。縣名以副總統理察·M·詹森 (曾任代表肯塔基州的眾議員、參議員)命名。