Asymmetrical ocean carbon responses to La Ni & ntilde;a and El Ni & ntilde;o complicate global carbon budget estimation. Using multiple ocean CO2 data products and an advanced ocean biogeochemical model, we identified significant asymmetries in ocean carbon magnitude, spatial distribution, and duration in the tropical Pacific Ocean. La Ni & ntilde;a enhances ocean CO2 outgassing (0.1-0.2 PgC/yr) with a broader poleward extension (15 degrees S-15 degrees N) for up to 3 years, while El Ni & ntilde;o reduces outgassing (0.2-0.4 PgC/yr) with a narrower poleward extension (10 degrees S-10 degrees N) for up to 1 year. The air-sea carbon flux anomaly shifts westward during La Ni & ntilde;a and eastward during El Ni & ntilde;o. These asymmetries are attributed to differing wind, precipitation, and ocean circulation anomalies between La Ni & ntilde;a and El Ni & ntilde;o. Additionally, the cumulative carbon flux remains slightly imbalanced, impacting the global ocean carbon sink balance. This study provides deeper insights into ocean carbon sink variability and highlights the need for enhanced monitoring of asymmetrical ocean carbon dynamics. Plain Language Summary The El Ni & ntilde;o-Southern Oscillation (ENSO) is a dominant factor in the interannual variation of global air-sea CO2 flux. In the ocean, ENSO manifests itself as a transition between El Ni & ntilde;o and La Ni & ntilde;a. Because of the asymmetry between the two, it may exert a non-zero forcing, inducing imbalanced carbon responses to ENSO. In this study, we have studied the asymmetry of air-sea CO2 flux caused by La Ni & ntilde;a and El Ni & ntilde;o events in the tropical Pacific Ocean. During La Ni & ntilde;a, ocean CO2 emissions to the atmosphere increase abnormally (0.1-0.2 PgC/yr), which lasts about 3 years with a broader poleward extension (15 degrees S-15 degrees N). During El Ni & ntilde;o, ocean CO2 emissions to the atmosphere decrease abnormally (0.2-0.4 PgC/yr), which is more intense and lasts about 1 year with a narrower poleward extension (10 degrees S-10 degrees N). What's more, the ocean carbon anomalies caused by La Ni & ntilde;a tend to be more westward than those caused by El Ni & ntilde;o. Our study shows that this is due to the combination of asymmetries in wind, rainfall, circulation anomalies, and biological processes. This study will help people understand the ocean carbon sink deeply and improve the accuracy of carbon budget estimation.