The therapeutic efficacies of oral nanotherapeutics for ulcerative colitis (UC) are seriously hindered by the lack of mucus-penetrating capacity and uncontrolled drug release. To overcome these limitations, the surface of poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles (NPs) was functionalized with pluronic F127 (PF127), and catalase (CAT)/curcumin (CUR) was co-encapsulated into these NPs. The obtained P-CUR/CAT-NPs had a hydrodynamic particle size of approximately 274.1 nm, narrow size distribution, negative zeta potential (-14.0 mV), and smooth surface morphology. Moreover, the introduction of PF127 to the surface of NPs not only facilitated their mucus penetration, but also improved their cellular uptake efficiency by the target cells (macrophages). We further found that the encapsulation of CAT could remarkably increase the release rate of CUR from NPs in the presence of an H2O2-rich environment. Additionally, P-CUR/CAT-NPs showed the strongest capacity to suppress the secretion of the main pro-inflammatory cytokines, in comparison with their counterparts (CUR-NPs and P-CUR-NPs). Importantly, oral administration of P-CAT/CUR-NPs showed the best therapeutic outcomes than the other NPs. Collectively, these results clearly demonstrate that these mucus-penetrating NPs loaded with CAT and CUR can be exploited as an efficient nanotherapeutic for UC therapy.