This randomized controlled trial investigated whether adding the psychodynamically based body-oriented psychotherapy "Functional Relaxation" (FR) to psychoeducation (PE) is more effective than PE alone to reduce stress and stress-associated complaints. Eighty-one participants with elevated stress-levels, >=50 points on the global scale of the Perceived Stress Questionnaire (PSQ), received either 10 sessions of manualized FR + PE ( = 42) or two sessions of manualized PE alone ( = 39) in a group setting. Six FR trainers took part in this study. Stress-level (PSQ) was the primary outcome and secondary outcomes were depression (PHQ-9) and somatization (PHQ-15). Multilevel models for discontinuous change revealed that FR + PE was more helpful to reduce stress-levels than PE from pre-treatment to post-treatment (t0 -> t1) as well as from pre-treatment to 6-month follow-up (t0 -> t2) (both < 0.05) with effect sizes () being medium for PE ( = 0.57; = 0.67) and large for FR + PE ( = 1.57; = 1.39). Moreover, FR + PE affected depression and somatization more positively than did PE from t0 to t1 as well as from t0 to t2 (all < 0.05). Effect sizes for depression were small to medium for PE ( = 0.52; = 0.37) and large for FR + PE ( = 1.04; = 0.95). Effect sizes for somatization were small for PE ( = 0.18; = 0.19) and medium to large for FR + PE ( = 0.73; = 0.93). In summary, the combination of FR and PE was more effective than PE alone. The results of the present trial provide first evidence of FR as a potent component of stress interventions. Adding FR to such interventions might better help prevent clinically relevant disorders such as depression or somatization.