On the major part of its course, the Sutla/Sotla River is a border river between Slovenia and Croatia. It joins the Sava as its left tributary near the settlement of Ključ Brdovečki, Croatia and the settlement of Rigonce, Slovenia.

There are many settlements lying in the Sutla/Sotla valley, such as Bračna Vas, Nova vas, Rigonce, Podčetrtek, Bukovje, Rakovec, Gregovce, Stara vas – Bizeljsko, Vonarje, Rogatec, Dobovec pri Rogatcu, Kunšperk, Polje pri Bistrici, Ples, Srebernik, Dekmanca, Lastnič, Polje ob Sotli, Sedlarjevo, Prelasko, Golobinjek ob Sotli, Imeno, Vidovica, Nimno, Pristavica, Rajnkovec, Rjavica, Tržišče and Trlično on the Slovenian side, and Hum na Sutli, Zalug, Prišlin, Mali Tabor, Poljana Sutlanska, Bratkovec, Harina Žlaka, Plavić, Zagorska Sela, Razvor, Kumrovec, Risvica, Ključ Brdovečki, Vukovo Selo, Harmica,  Kraj Donji, Gornji Čemehovec, Prosinec, Draše, Šenkovec, etc. on the Croatian side.