There is a consensus among researchers about the link between low meaning in life and anxiety and depressive symptoms. One unanswered question is whether meaning-making is a mediator of the change in anxiety and depression symptoms in participants with adjustment disorders during cognitive behavioural therapy (CBT) treatment. The aims of this study were (a) to analyse whether there was meaningmaking during the application of the CBT, (b) to analyse whether meaning-making was a mediator of anxiety psychopathology and (c) to analyse whether meaningmaking was a mediator of depressive symptoms. The sample was composed of 115 patients who satisfied the full Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 criteria for adjustment disorder as their primary diagnosis and completed CBT treatment in a primary care mental health service: 74.78% women, n = 86, and 25.22% men, n = 29, with a mean age of 41.89 (standard deviation [SD] = 10.39) years. The diagnosis was established using the Structured Clinical Interview for DSM-5 (SCID-5), and participants filled out the Beck Anxiety Inventory, the Beck Depression Inventory and Purpose in Life questionnaires. The therapists were clinical psychologists with experience in clinical assessment. A repeated-measures analysis of variance (ANOVA) and two mediation analyses using the bootstrap method were performed. The results indicated that (a) There was meaning-making during the CBT because the treated sample showed a statistically significant improvement in meaning in life, and (b) meaning-making during the CBT was a partial mediator between anxiety symptoms and depressive symptoms before and after the treatment. The present study suggests that meaning in life could be an important variable in the psychopathology of adjustment disorders.