We measure the branching fraction for the Cabibbo-suppressed decay D0→KS0KS0π+π- and search for CP violation via a measurement of the CP asymmetry ACP as well as the T-odd triple-product asymmetry aCPT. We use 922 fb-1 of data recorded by the Belle experiment, which ran at the KEKB asymmetric-energy e+e- collider. The branching fraction is measured relative to the Cabibbo-favored normalization channel D0→KS0π+π-; the result is B(D0→KS0KS0π+π-)=[4.79±0.08(stat)±0.10(syst)±0.31(norm)]×10-4, where the first uncertainty is statistical, the second is systematic, and the third is from uncertainty in the normalization channel. We also measure ACP=[-2.51±1.44(stat)-0.10+0.11(syst)]%, and aCPT=[-1.95±1.42(stat)-0.12+0.14(syst)]%. These results show no evidence of CP violation. © 2023 authors. Published by the American Physical Society.