The Širvinta is a river in Lithuania. Stretching for 129 km, it is the longest tributary of the Šventoji. Its source is in the hinterlands of the Širvintos district. After it passes through the town of Širvintos, where a low head dam has been built, it continues through the Ukmerge district, and borders the Jonava district. It ends when it flows into the Šventoji between Upninkai and Vepriai.