Within the municipal area, until German Reunification on 3 October 1990, lay the Federal Republic's geographical centre.

Rennerod lies in the Westerwald on Bundesstraße 54 between Limburg an der Lahn to the south and Siegen 30 km to the north.

The settlement's importance stemmed from its location on several trading roads that linked the Siegerland, Koblenz, Frankfurt, the Lahn area and Mainz.

Supposedly, the settlement would have been enclosed in the mid-11th century by the Counts of Diez, likely also to defend the Niederlahngau's northern border.

After the Counts of Diez, the Nassau lines of Nassau-Diez became the landlords, as of 1420 to half of Nassau-Dillenburg, and as of 1557 to three fourths, and as well to Eppstein-Königstein, the Electorate of Trier, Katzenelnbogen and the Landgraviate of Hesse.

As of 1564, Rennerod was wholly part of Nassau-Dillenburg, as of 1606 of Nassau-Beilstein, as of 1620 of Nassau-Hadamar, as of 1717 of Nassau-Diez, as of 1743 of Nassau-Orange and as of 1806 of the Grand Duchy of Berg.

Until 1591, Rennerod asserted itself against neighbouring Emerichenhain, which for a time also held the court seat.

As of 1775, Rennerod was once again the seat, keeping this function on into the time when it became Duchy of Nassau domain.

Several now forsaken villages are known to have lain within Rennerod's municipal area: Finkenhain, Himmenhain, Fackenhahn, Seiblingen, Seitenstein, Fuhrmannshof, Waldmühlen (occupied at least until 1811), Eichelerhof and Küchenhofen (forsaken no later than 1484) The council is made up of 20 council members, as well as the honorary and presiding mayor (Bürgermeister), who were elected in a municipal election on 13 June 2004.

Within the town, two Bundesstraßen, B 54 linking Limburg an der Lahn with Siegen and B 255 leading from Montabaur to Marburg, cross each other.

The nearest InterCityExpress stop is the railway station at Montabaur on the Cologne-Frankfurt high-speed rail line.