Mokronog parish was founded in 1649 or possibly three years earlier, since the presentation document was issued to the first parish priest appointed in Mokronog, Ivan Walli, on 20 April 1646. In 1753 the parish passed under the authority of the Archdiocese of Gorizia, thus ending the rule of the patriarchs of Aquileia in these parts. In 1784 it was incorporated into the Diocese of Ljubljana. In 2006 it passed to the Diocese of Novo Mesto.
The Church of St Giles is, of course, much older than Mokronog parish, and reliable references to it date from as early as 1349 or 1364, when it still formed part of the Šentrupert (St Rupert) parochial centre. The original church was rebuilt several times and remodelled in various styles. On 10 September 1811 the diocesan Ordinariate requested the municipal authorities to repair the dilapidated market town church, so that it would not pose a risk to the safety of the faithful. In 1815, however, before the repairs had commenced, the church collapsed. Work on a new church began in 1822 – on the site of the earlier church. Two years later, in 1824, the building and decorating of the Church of St Giles was complete, and on 23 December 1832 the diocesan Ordinariate proclaimed it a parish church. An important event for the parish church occurred in 1897 when a new pneumatic organ was purchased – the first of its kind in Carniola. The organ was built by Franc Goršič in Ljubljana. The next major alterations to the church began to be carried out in 1910, although they were interrupted the following year by the great fire that ravaged Mokronog. On 22 July 1913, however, a new marble altar, the work of a mason named Vatovec, was installed in the church. Another noteworthy event was the building of the new bell tower in 1940. Built by Franc Krištof of Mirna, the bell tower was designed by the architect Ivan Valentinčič. The interior of the church is Baroque in style; the image of St Giles on the high altar was painted by Matevž Langus, the painting on the left-hand side altar is by Henrika Šantel and the painting in the right-hand side altar is by local artist Anton Postl. The Way of the Cross was painted by Tomaž Perko.