Slovenia is situated in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. It lies between latitudes 45° and 47° N, and longitudes 13° and 17° E. The 15th meridian east almost corresponds to the middle line of the country in the direction west-east. The Geometrical Center of the Republic of Slovenia is located at coordinates 46°07'11.8" N and 14°48'55.2" E. It lies in Slivna in the Municipality of Litija. Slovenia's highest peak is Triglav (2,864 m or 9,396 ft); the country's average height above sea level is 557 m (1,827 ft).

Four major European geographic regions meet in Slovenia: the Alps, the Dinarides, the Pannonian Plain, and the Mediterranean. Although on the shore of the Adriatic Sea near the Mediterranean Sea, most of Slovenia is in the Black Sea drainage basin. The Alps, including the Julian Alps, the Kamnik-Savinja Alps and the Karavanke chain, as well as the Pohorje massif, dominate Northern Slovenia along its long border with Austria. Slovenia's Adriatic coastline stretches approximately 47 km (29 mi) from Italy to Croatia.

The term "Karst topography" refers to that of southwestern Slovenia's Kras Plateau, a limestone region of underground rivers, gorges, and caves, between Ljubljana and the Mediterranean. On the Pannonian plain to the East and Northeast, toward the Croatian and Hungarian borders, the landscape is essentially flat. However, the majority of Slovenian terrain is hilly or mountainous, with around 90% of the surface 200 m (656 ft) or more above sea level.

Over half of the country (10,124 km² or 3,909 sq mi) is covered by forests. This makes Slovenia the third most forested country in Europe, after Finland and Sweden. The areas are covered mostly by beech, fir-beech and beech-oak forests and have a relatively high production capacity. Remnants of primeval forests are still to be found, the largest in the Kocevje area. Grassland covers 5,593 km² (2,159 sq mi) and fields and gardens (954 km² or 368 sq mi). There are 363 km² (140 sq mi) of orchards and 216 km² (83 sq mi) of vineyards.

Slovenia is in a rather active seismic zone because of its position to the south of the Eurasian Plate. Thus the country is at the junction of three important tectonic zones: the Alps to the north, the Dinaric Alps to the south and the Pannonian Basin to the east. Scientists have been able to identify 60 destructive earthquakes in the past. Additionally, a network of seismic stations is active throughout the country. Many parts of Slovenia have a carbonate ground, and an extensive subterranean system has developed.