Schizoid personality disorder (SPD) has been characterised by a persistent detachment from, and indifference to, interpersonal relationships, alongside restricted range of expressed emotions, and limited rewards gained from social interactions, resulting in limited levels of socially healthy behaviour. Although the applicability of evidencebased psychological treatments, including cognitive therapy (CT), has been indicated, there is a noticeable scarcity of relevant academic literature that might inform clinical practice in mental health clinics. This rigorous single subject design study attempts to address such apparent gap in literature. Sixteen sessions of CT were undertaken with an individual diagnosed with SPD and comorbid mood disorder in a community-based mental healthcare setting. Formal standardised measurement, behaviour frequency sampling, and subjective data were utilised to systematically evaluate the outcomes, indicating a considerable improvement in psychosocial functioning. The paper highlights the pertinence of cognitive and behavioural strategies in helping schizoid individuals address their interpersonal difficulties, reduce emotional distress, acquire socially inclusive behaviour, and ultimately increase their psychosocial health, without the need for explicitly intervening with their underlying personality traits.