Although the positive effect of nature connectedness (NC) on eudaimonic and hedonistic wellbeing is confirmed by numerous studies, the question of intrapersonal processes that determine such an impact remains open. Wilson’s biophilia hypothesis points to the evolutionary background of NC, as this can be considered pre-trust as an evolutionarily formed trust to the ecological world, to life in its diverse manifestations (Petzold, 2012). It is suggested that pre-trust sets a vector of positive comprehension on what happens while NC actualizes pre-trust, thereby launching a ‘system of psychological wellbeing maintenance’. The hypothesis that trust is a mediator between NC and psychological well-being was tested in two studies. Multiple regression and mediation analysis, and structural equation modeling (SEM) were applied. Study 1 (the sample comprised 232 Ukrainian university students) confirmed the model of the NC influence on positive functioning (Ryff's Psychological well-being scale and Hardness test were applied) with trust as a mediator. Study 2 (the sample comprised 276 Ukrainian and Belarusian university students) showed that a latent variable manifested by trust and a sense of coherence index mediated the relationship between NC and subjective well-being. It is shown that trust in oneself is included in support of positive functioning, while subjective wellbeing is supported by experiencing the meaningfulness of life events. Limitations of the studies and their implications for conservation psychology are discussed.