Suicide is a serious but preventable public health concern at the global level, showing relevant geographical differences. This study aims to monitor global temporal and geographical patterns in suicide mortality in pre-adolescents, adolescents, and young adults (i.e., aged 10–24 years), from 1990 to 2020 or the most recent available year. Using the World Health Organisation mortality database, we conducted an analysis on a subset of 52 countries with valid and high-quality data. We computed age-standardised suicide rates (ASR) by sex, country, and calendar year, and performed a joinpoint regression analysis to identify significant changes in the temporal suicide trends over the studied period. High variability in suicide rates and trends was observed, with a male-to-female ratio of two to five. Between 1990 and 2020, most European countries reported declining suicide trends, with some exceptions. In particular, alarming trends emerged in the United Kingdom, with annual rises of 2.5% (95% CI: 1.6–3.5) since 2005 among males and 8.5% (95% CI: 4.7–12.6) since 2012 among females. The most favorable trends and lowest suicide rates were in Southern Europe, with 3.1/100,000 persons in Italy (2020) and 3.5/100,000 persons in Spain (2021) among males, and 0.9/100,000 persons in Italy (2020) and 1.1/100,000 persons in Romania (2019) among females. Conversely, the highest rates were in Central-Eastern Europe, with 10.2/100,000 males in the Russian Federation (2019) and 10.0/100,000 males in Poland (2002). Higher suicide rates and significant increases were reported in not European areas. The highest ASR was 15.5/100,000 males in the United States of America, with an annual increase of 3.8% (95% CI: 3.1–4.5) among males in 2009–2020 and 6.7% (95% CI: 5.6–7.8) among females in 2007–2017, followed by a levelling off. Temporal and geographical comparisons of suicide mortality should be interpreted with caution due to potential misclassification or under-reporting of suicide deaths in some countries. None.