Studies have found that extraversion enhances happiness indirectly through social support. However, it is unclear how social support may be connected to happiness. On the basis of a literature review, we hypothesize that individual hope may play an important role in the relationship between social support and happiness. Using a serial mediation model, the present study attempted to investigate the hypothetical mediating role of hope in the relationship between extraversion and happiness and between social support and happiness. Analysis of responses of 360 undergraduate students showed that extraversion, social support, and hope were significantly linked with happiness. Moreover, hope was found to mediate the linkage of extraversion and happiness and of social support and happiness. The results also supported the view that extraversion enhances happiness through social support and then hope (serial mediating effect). Lastly, the serial mediating effect was found to be significantly lower than the other two indirect effects. The findings offer insights into the effect of social support on happiness and extend the understanding of the relationship between extraversion and happiness.