Internalized stigma (IS), in addition to the illness itself, is one of the major challenges that people with mental health problems have to face. The aim of this scoping review and meta-analysis is to update knowledge about this issue and to investigate the influence of different sociodemographic, psychosocial, and clinical variables on IS. English and Spanish articles were searched between 2010 and 2019, in different databases, with no restriction on culture or geographical area. Only studies that used the Internalized Stigma of Mental Illness Scale (ISMI) as a measure of IS were included. A total of 61 studies remained for the review and 52 for the meta-analysis (N = 11,072). Self-esteem, quality of life, hopeful feelings and stigmatizing experiences, as well as clinical variables (depressive symptoms and subjective recovery), were strongly associated with IS. The association of insight with IS was not confirmed. Empowerment showed a weaker relationship than in a previous meta-analysis. Gender and age, education, occupational situation, and marital status were weakly associated with IS, and sometimes inconsistently. Subjective recovery, depressive symptomatology, or experienced and perceived social stigma have begun to be studied in recent years. The update on the subject reveals the impact of clinical and psychosocial variables, also underlining the relevance of recently incorporated variables such as depressive symptomatology, subjective recovery, and perceived discrimination. The results highlight the need to carry out longitudinal studies with more representative samples and in new geographical areas with variables rarely or not yet studied in relation to IS.