This study sought to explore the possibility of art therapy in a new environment: using online art therapy to relieve depression and parenting stress of mothers of preschoolers who practice social distancing due to COVID-19. The research subjects were five mothers of preschoolers recruited through an online network. The online art therapy was conducted individually, twice a week, 50 minutes per session, from April 23 to June 5, 2020. In order to examine the changes in participants, the following pre- and post-tests were conducted: Beck Depression Inventory (BDI), Korean version of the Parenting Stress Index-Short Form (K-PSI-SF), Kinetic Family Drawing (KFD), and People in the Rain (PITR). To improve the environment of online art therapy, a questionnaire was conducted after. The results of this study were as follows: First, mothers’ depression was alleviated using online art therapy. Second, parenting stress was able to partially relieved, and positive emotional changes were observed through the drawing test. Third, art therapy in the online space has the potential to be a therapeutic environment through the expansion of opportunities for participation in time and space and smooth interaction with therapists. This study is meaningful to raise the possibility of a new therapeutic environment through online art therapy. However, discussion about the safety of patients in the online space and the protection of personal information by therapists are still needed.