Introduction: Global research has explored the relationship between trait mindfulness and problematic usage of the internet (PUI), an umbrella term encompassing uncontrolled, excessive, and potentially harmful online behaviors with significant individual and societal costs. Relatedly, studies have examined trait mindfulness in relation to screen time and nomophobia (i.e., the discomfort from having no access to one?s technology). Methods: We systematically searched eight databases from inception to April 04, 2024 with no language restrictions. Results: We included 140 studies involving 79,080 participants. A medium negative relationship between overall trait mindfulness and PUI (k 5 120; r 5
0.38) was found. Specific facets of trait mindfulness, including Acting with awareness (k 5 19; r 5
0.42), Non-judging of experience (k 5 16; r 5
0.24), and Describing (k 5 14; r 5
0.11) were negatively associated with PUI, while Non-reactivity to inner experience (k 5 13; r 5
0.07) and Observing (k 5 14; r 5 0.03) were not. Small negative correlations were observed between trait mindfulness and screen time (k 5 17; r 5
0.11) and nomophobia (k 5 12; r 5
0.26). Relationships were robust in sensitivity analyses, such as excluding outliers or low quality studies, or using longitudinal data. No publication bias was observed. Discussion and conclusion: Individuals with higher trait mindfulness tend to exhibit fewer signs of PUI and nomophobia and report slightly less screen time. Trait mindfulness may protect against future PUI. High-quality, more fine-grained longitudinal research is needed to explore how specific facets of mindfulness, PUI subtypes, and screen time interact.  Kulcsszavak: trait mindfulness, problematic usage of the internet, screen time, nomophobia, meta-analysis, longitudinal