In the early Middle Ages the area of the county of Radom was ruled by local castellans. The county of Radom was created in the first half of the 14th century with the introduction of a new new court and treasury division. The county of Radom was a part of Sandomierz province that was originally made up of nine counties. In 1476 the reform of structure of landed courts reduced their number to seven, keeping the following counties: Sandomierz, Wiślica, Chęcin, Opoczno, Stężyce and Pilzno, as well as the county of Radom.
Before it was incorporated into Sandomierz province in the 13th century, the Radom Land had been a disputable area and dukes of Mazovia and Małopolska rulers competed for the reign in this territory. The Mazovian rule ended in 1243 after the battle of Suchodół. The last duke of Mazovia who managed to keep rule in the vicinity of Radom was Bolesław, son of Konrad Mazowiecki.
The county of Radom formed in the Middle Ages was nearly three times bigger than it is now and its eastern and northern boundary coincided with boundaries of Sandomierz province. It was bordered by the county of Opoczno to the west, and the county of Sandomierz to the south. Boundaries of church administrative units were more complicated. Most of the county belonged to Krakow diocese, and the western territory – to the archdiocese of Gniezno. The county of Radom was the second biggest county in the Sandomierz province with the territory of 5,241 km2 in the second half of the 16th century. It was populated by 72 thousand people. There were 613 settlements in this region, including 22 towns. By the end of the 18th century the number of towns increased to 28 and the population of the county increased nearly twice. Among the present administrative units of the county of Radom the following had civic rights: Iłża, Jedlińsk, Skaryszew, Przytyk, Wierzbica and Wolanów.
In terms of geography and nature, the contemporary county of Radom was situated in the Środkowopolskie Lowlands. Only the southern edge between Iłża and Szydłowiec was in the Środkowomałopolska Upland. The county was situated in the Vistula basin and intersected by its left-side tributaries: the Kamienna, the Iłżanka, the Radomka, the Pilica and the Zwolenka. Among natural resources, deposits of iron ore by the Kamienna River, clay deposits near Iłża and sandstone deposits near Szydłowiec were the most significant ones. The county was quite densely afforested. From Ryczywół in the north to Zwoleń and Tczów in the south, as far as to the Vistula river in the east, the Jedlneńska Forest extended. Since the second half of the 16th century its part has been referred to as the Kozienicka Forest.
Over ages, the Radom Land was an area for historical events significant for the whole Republic of Poland. For a couple of times the county suffered from Tartar invasions, by which Iłża and Skaryszew were destroyed. In the 14th century Lithuanian invasion also reached this territory. The reformation, however, the prime of which was mid 16th century, developed to a smaller extent than in other regions. Big losses were induced by the Zebrzydowski Rebel in 1606 1609, Swedish Invasion in mid-17th century and The Great Northern War at the beginning of the 18th century.
Settlements developed mainly on the edge of the Jedlneńska Forest. Along with the property of knight families, church property developed: the Sieciechów Abbey in the east, Krakow bishops in the south and bishops of Gniezno and Poznań in the west. The oldest wave of settlers came mainly from Mazovia; settlers from Małopolska also arrived to the southern parts. At the end of the 13th century the distribution of property was established between the duke (mainly territories to the east of Radom), the church (southern territories surrounding Skaryszew, Dzierzkówek, Iłża and eastern territories around Sieciechów) and the nobility occupying territories in the west and in the north. In the 14th and 15th century considerable part of property was taken over by private owners. The biggest landowners were the members of Łabędź, Rawicz, Doliw and Odrowąż families. The end of the 15th century brought about dynamic development of manor farming. However, a typical royal manor was not big, on average it was 53 ha.
Property of the nobility was extended at the expense of royal property. Among the cities granted civic rights in the 15th century five were owned by the nobility, four by the church and only one was a royal property. In the 15th century, property of the nobility extended over 63% of the county already, church property was 21% and royal – 16%. This situation has not changed to a greater extent by the end of the First Republic of Poland. However, increasing significance of the biggest landowners was noticeable. At the end of the 18th century there were 31 representatives of rich nobility and magnates with the income bigger than 5 thousand zlotys. The biggest church property was the Iłża estate of the Krakow bishops comprising 30 settlements. Peasants were the most numerous social group. In the mid-16th century there were about 32 thousand farmers, 6 thousand yeomen, 2 thousand tenants, 740 craftsmen, 3 thousand innkeepers, 1 thousand millers, 550 blacksmiths. The plebeian population working on manor fields was about 9 thousand.
Following the Third Partition, the county of Radom was incorporated into a district, and then – in 1810 – department of Radom. In 1816, provinces were restored in the Polish Kingdom, including Sandomierz province with the seat in Radom, divided into 4 administrative districts and 10 counties. In 1817-1837 slight territorial changes occurred including an incorporation of a few villages now situated at the boundary of the county of Radom and Szydłowiec. In 1837 the name ‘province’ was changed into ‘gubernyia’. In 1842 administrative districts were renamed counties and counties were renamed districts.
After the fall of the January Insurrection offices were reformed according to the Russian pattern and filled with tsar’s officials. The Radom gubernyia was divided in 1867 into two: Kielce gubernyia and Radom gubernyia. In 1915-1918 the Central Powers divided the territory of the Kingdom into two zones: German and Austrian one. Since 1st September 1915, the Governor-General’s territory with the seat in Kielce, and later in Lublin extended over 14 counties, including the county of Radom. In 1919 the Radom Land was incorporated into the newly-formed Kielce province; in the same year the county offices were renamed county administrative offices. After the World Wars the general administrative division was introduced by the reform in 1954. In the county, groups of villages were formed in place of communes; such territorial division lasted until 1973, when the communes were reintroduced. Two years later the area of the provinces was reduced, counties were liquidated and the considerable part of their competence was transferred to communes. At that time 49 provinces were formed, including Radom province made up of 63 communes and 16 towns, covering the area of 7,294 km2 and inhabited by 763 thousand people (1994).
The present administrative division of the country, introduced by the law of 5th June 1998, reactivated the county of Radom, incorporating it into the Mazovia province.