The photocatalytic degradation of methylene blue (MB) dye using Lanthanum (La) and Iodine (I) co-doped TiO2 (Ti1−x-yLaxIyO2, where x = 0.00 – 0.05, y = 0.00 – 0.005) nanoparticles prepared through the solution combustion method has been investigated in the current study. The photocatalysts' characterization was done using various techniques, including FTIR for identifying functional groups, XRD for determining crystallinity and crystallite size, DRS for estimating the band gap, and XPS for identifying elements and their oxidation states. The co-doping of La and I in TiO2 causes narrowing the band gap and suppresses the recombination of e–/h+ pairs, which surges its photocatalytic activity. The La and I co-doped TiO2 nanoparticles exhibited a photodegradation efficiency of 98% for MB within 40 min, significantly outperforming undoped TiO2 and commercial TiO2 photocatalyst Aeroxide P-25. Moreover, regeneration experiments demonstrated excellent reusability of the nanoparticles. To find potential use of photocatalytically treated water in irrigation, the phytotoxicity study was done with "Vigna radiata" germination. The evaluation of phytotoxicity demonstrates that the treated water may be used for irrigation purposes.