Background The dramatic reconfigurations of work-family roles and social boundaries resulting from the social restrictions imposed during the Covid-19 pandemic led working mums to look for online sites as spaces of emotional support and regulation where they could vent their emotions, share their concerns and griefs, and seek advice. They also became interactional spaces where mums’ relevant identities were reassessed and enacted as they aimed to balance work-family roles and improve their wellbeing. The paper explores how working mums discursively negotiated their multiple identities in an online support forum during times of global struggle, how these identity constructions reflect the domains of Work-Family Conflict (WFC) and how working mums perceived these identities are related to their mental health. Methods 127 posts of Chilean working mums published in a public online support forum for working mums collected during the first half of 2020 were analysed in three phases. The first one involved a thematic analysis to identify themes and subthemes related to working mums’ identity construction in the data. The second phase involved conducting a narrative analysis of working mums’ microstorias in order to identify a master narrative crafted by these working mums, and contesting and conforming ideologies of motherhood, among others. Finally, the third phase involved a fine-grained discourse analysis of the most representative extracts illustrating working mums’ identity negotiation. Results The sociolinguistic analysis showed that working mums’ discourses displayed three themes of self-reflection, namely, diminishing self-care, reassessing their self, and enhancing self through self-care. Identity-related sub-themes for each main theme are discussed and discursively analysed. Two main points are emphasised: (1) the identity that was most salient in working mums’ discourse was their personal identity (rather than work-family roles and identities), and (2) microstorias allowed working mums to challenge the hegemonic power of dominant discourses around their identities and their work-family roles. Conclusions The study shows that a sociolinguistic approach to the exploration of working mums’ identity negotiation is useful to highlight the ways in which mums contest binary assumptions of work-family roles and the need to reconsider working mums’ life domains so that they reflect working mums’ actual identity needs and lived experiences. Future lines of research are outlined.