To enhance the gas–liquid mass transfer in the hydroformylation reaction, microbubbles were applied into this typical gas–liquid reaction. Compared with a commercial tube microbubble generator, a fractal microbubble distributor, which was designed based on the bionic fractal theory and manufactured via 3D printing, permitted to increase the total microbubble number and decrease the microbubble size. Moreover, the microbubbles were more uniformly distributed in the reactor by the fractal distributor. The gas holdup and the gas–liquid mass transfer were much higher in microbubble system than those with millimeter bubbles. The microbubble status played an important role on the hydroformylation performance. With a close total aldehyde yield (90%), the introduction of microbubbles could reduce the hydroformylation reaction time from 120 min of the stirred batch reactor to 60 min owing to the enhanced mass transfer. The proposed microbubble mediated system also has great potential for intensifying the other gas–liquid reactions.