This study aimed to longitudinally analyze the role played by two emotional regulation strategies (cognitive reappraisal and expressive suppression), through the mediating effect of engagement in pleasant activities during lockdown, in changes in affective and cognitive happiness in comparison with pre-pandemic levels . Eighty-eight participants from a community sample were evaluated at two timepoints . At timepoint 1 (before the COVID-19 pandemic), participants were evaluated on emotional regulation and cognitive and affective happiness . At timepoint 2 (during the COVID-19 lockdown), participants were evaluated on cognitive and affective happiness and the frequency with which they engaged in pleasant activities . We found an optimal fit of the proposed model in which cognitive reappraisal was significantly related to engagement in more pleasant activities during the lockdown . In turn, these pleasant activities were related to more affective happiness during the lockdown (compared with pre-pandemic levels), and this affective happiness was associated with greater cognitive happiness . In conclusion, cognitive reappraisal was a protective factor for affective and cognitive happiness through the mediating role of engagement in pleasant activities during lockdown . Limitations and future lines of investigation are discussed.