Single-parent adolescents are vulnerable individuals and it is necessary to improve their health, particularly during epidemics. This study aimed to investigate the effects of virtual logotherapy (VL) on health-promoting lifestyle (HPL) among single-parent adolescent girls during the COVID-19 pandemic. This single-blind randomized clinical trial was conducted on 88 single-parent adolescent girls recruited from the support organization for vulnerable individuals in Tehran, Iran. They were randomly allocated to a control and an intervention group through block randomization. Participants in the intervention group received VL in three–five person groups in 90 min biweekly sessions. The Adolescent Health Promotion Short-Form was used to assess HPL. Data were analyzed using the SPSS software (v. 26.0) and through the independent-samplet, Chi-square, Fisher’s exact, and Mann–WhitneyUtests. There was no significant difference between the intervention and the control groups respecting the pretest mean score of HPL (73.58±16.74 vs. 72.80±9.30;P=0.085). However, the posttest mean score of HPL in the intervention group (82 with an interquartile range of 78–90) was significantly more than the control group (71.50 with an interquartile range of 63.25–84.50) (P=0.001). Moreover, after adjusting the effects of the significant between-group differences respecting pretest mean scores, the pretest–posttest differences of the mean scores of HPL and all its dimensions in the intervention group were significantly more than the control group (P<0.05). VL is effective in significantly improving HPL among single-parent adolescent girls. Healthcare authorities are recommended to use VL for health promotion among single-parent adolescents.Trial registrationThis research was registered (17/05/2020) in thewww.thaiclinicaltrials.orgwith registration number: TCTR20200517001.