Abstract Objective To evaluate the color adjustment potentials of monoshade universal composites in different shades of class I cavities. Methodology About 132 restorations were performed using monoshade universal composites (Omnichroma, OMNI; Essentia Universal; EU; Charisma Diamond One, CDO), and one simplyshade composite (NeoSpectra-ST, NEO) as control. A transparent silicone mold was used to provide standardized restorations on prefabricated class I cavities of acrylic dentures in B1, A2, and C4 shades. The assessment of color adjustment was performed immediately after, at 24 h, and at 2 weeks, through the cross-polarized dental photographs. The quantitative assessments were performed using a software (Digital Color Meter, Macintosh AC). The collected L*, a*, and b* coordinates from the restorations and the adjacent denture surfaces were used to provide Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values. Shapiro–Wilk, three-way Anova and Tukey HSD Test were used for the statistical analyses (p < 0.05). Results Among all composites and shades, the Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values were significantly the highest (1.27 ± 0.49a) for the immediately after assessments compared to the assessments at 1 day (1.01 ± 0.41b) and 2 weeks (0.97 ± 0.4c)(p < 0.05). At 24 h and 2 weeks of evaluations, the Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values for the control (0.42 ± 0.16H) were significantly the lowest (p < 0.05). Only the control presented imperceptible color changes for all the cavity shades (PT ≤ 0.8). After 2 weeks, EU (1.06 ± 0.32F) and OMNI (1.12 ± 0.18EF) presented significantly lower Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values compared to the CDO (1.29 ± 0.2CD) (p < 0.05). Restorations in lighter cavities presented significantly lower Δ E 00 ⁎ \text{&#x0394;}{E}_{00}^{\ast } values. Conclusion Monoshade universal composites presented acceptable but perceptible color adjustment potentials in class I cavities without the shade selection procedure. Simplyshade composites following the shade selection might still be the best options regarding the level of color adjustment. Monoshade universal composites might provide better color adjustments in cavities with lighter shades.