The feeling of happiness is beneficial for both mental and physical health. Based on the findings of previous studies that reported that the insular cortex is a crucial region for subjective feelings, including happiness, in this study, we further identified the subregion of the insula and its functional connectivity associated with subjective well-being (SWB). Using an iterative seed-target-seed approach, we labelled the posterior, dorsal, and ventral anterior insular regions of interest (ROIs) and evaluated the association between functional connectivity of each of these insular ROIs and the self-reported SWB in a group of 75 healthy elderly adults. We demonstrated that the functional connectivity of the dorsal anterior insula (dAI) was significantly correlated with SWB. This relationship was negative and unique for the functional connectivity of left dAI with specific regions from the default-mode network, including the anterior medial prefrontal cortex and inferior parietal lobe. Our result suggested a functional connectivity network of the left dAI with specific DMN brain regions, suggesting the neural basis of SWB.