Robot-assisted therapy (RT) and constraint-induced therapy (CIT) both show great promise to improve stroke rehabilitation outcomes. Although the respective treatment efficacy of RT and CIT has been validated, the additive effects of RT combined with CIT remain unknown. This study investigated the treatment effects of RT in sequential combination with a distributed form of CIT (RT + dCIT) compared with RT and conventional rehabilitation (CR). Forty-eight patients with stroke were enrolled and randomized to receive one of the three interventions for 4 weeks. Primary outcomes assessed the changes of motor impairment and motor function on the Fugl-Meyer Assessment (FMA) and Wolf Motor Function Test (WMFT). Secondary outcomes, including the Motor Activity Log (MAL) and accelerometers, examined functional performance during daily activities. The three treatment groups improved significantly on most primary and secondary outcomes over time. The combined RT + dCIT group exhibited significantly greater improvement on the FMA and functional ability subscale of the WMFT than the RT and CR groups. The improvements on the MAL and accelerometers were not significantly different among the three groups. RT in sequential combination with CIT led to additive effects on participants' motor ability and functional ability to perform motor tasks after stroke, which support that combined therapy can be an effective means to intensify outcomes. Further research investigating the potential long-term effects of combination therapy, especially on real-life performance, would be valuable.