© 2019 Elsevier B.V. The present study is focused on the synthesis of a novel solar light responsive bismuth doped titania (Bi-TiO2) through a facile so-gel technique by applying various wt% of Bi. The as-synthesized Bi-TiO2 showed superior photocatalytic performance than un-doped TiO2 towards degradation of flumequine (FLU) under solar light irradiation. The as-synthesized material was thoroughly characterized to examine its structure, morphology and chemical states. The EPR analysis revealed the existence of Ti3+ ion and oxygen vacancy, which is created due to Bi-doping. The as-synthesized Bi-TiO2 with 5 wt% Bi (TBi5) showed excellent photocatalytic performance as compared to their counterparts. The photocatalytic activity of TBi5 was further improved when added with peroxymonosulfate (HSO5−) and increased with increasing [HSO5−]0. The mechanistic investigation and radical scavenging studies revealed that [rad]OH and SO4[rad]− are involved in the degradation of FLU by the as-synthesized material. The bimolecular rate constants of [rad]OH and SO4[rad]− were calculated to be 9.1 × 109 M−1s−1 and 8.5 × 109 M−1s−1, respectively. The photocatalytic performance of the as-synthesized TBi5 coupled with HSO5− under solar light irradiation towards degradation of FLU in Milli-Q water (MW), tape water (TW) and synthetic wastewater (SWW) was 92, 82 and 70% with kapp values of 0.093, 0.085 and 0.066 min−1, respectively. Furthermore, the degradation pathways of FLU were predicted on the basis of its degradation products (DPs). The high mineralization of FLU as well as the evaluation of non-toxic DPs suggests that solar light/TBi5/HSO5− is a promising advanced oxidation process for the future wastewater treatment applications.