Abstract In Thailand, cardiovascular disease and mental health cause a large health and economic burden, with 10% of Thai adults and 32% of adolescents reporting depression. Forest bathing (FB) (mindful nature walking) is growing in popularity globally as a preventative health intervention. Most FB research compares FB with a non‐active control of unguided urban walking, finding improved health and well‐being in FB but not the urban condition. This controlled trial offers a unique and robust comparison of guided FB with an active control of guided mindful urban walking. This is also the first study testing the acceptability and effectiveness of guided FB in Thailand. In a crossover design, heart rate, heart rate variability, blood pressure, and mood in 30 participants were compared before and after 1 h of guided FB and a guided mindful urban walk. MANOVA and t‐test analyses revealed that heart rate and blood pressure reduced in both conditions, but more in the mindful urban condition. Whilst negative mood was reduced in the FB condition but increased in the mindful urban condition. The study offers evidence for the promising health and well‐being benefits of both guided FB and mindful urban walking. Poor mental health and health inequalities are of increasing global concern, hence further research into the effectiveness of alleviating these difficulties through inexpensive interventions such as guided FB and mindful walking are encouraged. The study also offers the first data indicating that FB was acceptable and effective in a Thai population. Read the free Plain Language Summary for this article on the Journal blog.