The municipality lies at the foot of the mountain Pilatus, and is a western suburb of Lucerne.

The City of Kriens consists of the ("citified") town of diverse districts, the community of Obernau to its west, the hamlet of Hergiswald, 5 km to the west of the town on the road to Eigenthal, and numerous independent farmsteads on the slopes of Pilatus.

The border in the east, with the neighboring community of Lucerne, goes across the property of a large brewery.

From there it follows the (partially former) train track toward Lucerne in a north-easterly direction back to the property of the brewery.

The eastern part of Kriens (the districts near the city and near Horw) lie in a valley.

To the north of the town is the small, forested southern slope of Mount Sonnenberg.

The lower part is cleared and partially developed, however the majority of the land west of Obernau and south of town is forest.

West of the line connecting Krienseregg and Fräkmüntegg there is a large, flat swamp, from which is the starting point of many brooks (including Tschuggenbach, Weissbach, Rotbach, and Renggbach).

The Schlundbach and the previously mentioned Steinibach flow in the direction of Horw and onward into Lake Lucerne.

Of the rest of the land, 16.9% is settled (buildings or roads) and the remainder (1%) is non-productive (rivers, glaciers or mountains).

Of the settled areas, 8.81% is covered with buildings, 2.23% is industrial, 0.84% is classed as special developments, 1.1% is parks or greenbelts and 3.88% is transportation infrastructure.

Kriens borders on Hergiswil to the south, on Horw to the south and east, on the City of Lucerne to the east, the former municipality Littau (now part of the City of Lucerne) to the north, on Malters to the north-west, and on Schwarzenberg to the west.

At the time of the last census in 2000[update], 89.36% responded that their main language was German, 2.55% Italian, and 1.92% Serbian.

As of 2000[update], the religious demography was as follows: The majority of the Muslims are Albanian and Bosnian, along with some other nationalities.

The Jews are generally members of the (orthodox) Hasidic branch of Judaism, and Swiss in nationality.

In contrast to the other large municipalities in Lucerne, there are no communities with a foreign immigrant majority in Kriens.

As the tracks were laid in the road, they were in the way and were finally removed 2004, when the town centre was redeveloped.

The Kriens-Mattenhof station opened on the rail line between Lucerne and Interlaken/Engelberg in December 2004.

However, the station is closer to Horw and parts of Lucerne than to the city centre of Kriens.

Line 1 of the VBL bus company goes from Lucerne to Kriens-Obernau via the town center and Line 5 connects Kriens directly to Emmenbrücke, not serving the city centre of Lucerne.

Additionally, the bus lines 14 and 21 go from Lucerne to Kriens, partially via Horw.

Kriens has its own exit on the A2 motorway near Grosshof, south of the Mount Sonnenberg tunnel.