Tandem light-emitting diodes (LEDs), achieved by vertically stacking multiple units in series to combine the luminance of individual light-emitting elements, are effective for improving efficiency and lifespan compared to single-unit devices1–3. In particular, tandem perovskite LEDs benefit from the small Stokes shifts of perovskites4, which in principle can enable significant photon recycling between individual perovskite layers and enhance light extraction from trapped modes. However, a tandem structure that effectively merges the luminance of each perovskite units still remains a significant challenge. Here, we demonstrate efficient and stable tandem LEDs by combining two solution-processed perovskite light-emitting units. This tandem structure effectively combines the original luminance of each light-emitting units; we argue that the emissions are also significantly enhanced through photon recycling between the individual light-emitting units. Consequently, we achieve tandem perovskite LEDs with a low turn-on voltage of 3.2 V, a high peak external quantum efficiency (EQE) of 45.5% (even 20% higher than the sum of peak EQEs of single-unit devices), an average peak EQE of 40.9%, and a half-lifetime of 64 h at an initial radiance of 70 W Sr−1 m−2. These findings represent a significant advancement in achieving high-performance and multicolor LEDs through the stacking of perovskite LEDs.