<p>Many countries have adopted low-carbon regulations to encourage enterprises to invest in green technology. However, uncertainties of technology investment and technological spillover can diminish enterprises’ investment enthusiasm. Motivated by this reality, we investigate the impact of the cap-and-trade mechanism on manufacturers’ investment decisions when there exists technology spillovers and uncertainty. To portray technology uncertainty, we consider two manufacturers making green technology investments with a certain probability of success. Covered by the cap-and-trade mechanism, we discuss equilibrium decisions, profits, and social welfare under different carbon quota allocation mechanisms (benchmarking or grandfathering) and cooperative modes. Several important conclusions are drawn. First, when the technological spillover effect is high, manufacturers tend to increase their green technology investment in the cooperative mode, which generates higher member profits, consumer surplus and social welfare. Second, a benchmarking mechanism is more likely to incentivize manufacturers to invest in green technology and improve production than a grandfathering mechanism. Finally, if the total carbon quota is below a certain threshold, the government can benefit from implementing the benchmarking mechanism. These findings provide novel managerial insights for manufacturers to harness green technology spillovers when facing different carbon cap-and-trade mechanisms.</p>