The WTA 125K series is the secondary professional tennis circuit organised by the Women's Tennis Association. The 2019 WTA 125K series calendar consists of eleven tournaments, each with a total prize fund of $125,000 except the Oracle Challenger Series that offers $162,480 in prize money. Starting from 2019, Zhengzhou Open was upgraded to a WTA Premier level event while the Mumbai Open was cancelled due to elections in the city. The Oracle Challenger event in Chicago was replaced by another one in New Haven. Three new Challenger events were introduced in Guadalajara, Båstad and Karlsruhe.