Neighboring provinces are (from north clockwise) Sakon Nakhon, Mukdahan, Roi Et, Maha Sarakham, Khon Kaen, and Udon Thani.

On the northwestern creek of the reservoir, a road bridge connects the village of Ban Dong Bang in the west with the district town of Wang Sam Mo in the east.

The Phu Phan mountain range marks the border with Sakhon Nakhon province, part of which is preserved as a national park.

Kalasin is an agricultural province producing sticky rice and other cash crops such as manioc (cassava) and sugar cane.

Similar inscriptions have also been found in Maha Sarakham and Khon Kaen provinces, highlighting the broader importance of this discovery for the study of the Dvaravati period in Northeastern Thailand.

During the Thesaphiban reforms in the reign of King Rama V at the beginning of the 20th century, the town (mueang) was upgraded to a province.

As of 26 November 2019 there are:[14] one Kalasin Provincial Administration Organisation (ongkan borihan suan changwat) and 79 municipal (thesaban) areas in the province.

The non-municipal areas are administered by 71 Subdistrict Administrative Organisations - SAO (ongkan borihan suan tambon).