Background/Objectives: In vitro fertilization (IVF) is an assisted reproductive technique for women and couples experiencing difficulties in achieving a spontaneous pregnancy, often due to stressors that negatively affect fertility. Humor can be beneficial in these stressful situations, helping to reduce symptoms of anxiety and depression. The primary aim was to analyze the effectiveness of laughter therapy in increasing pregnancy rates in women undergoing IVF. The secondary aims were to identify different types of laughter therapy interventions and evaluate their benefits. Methods: A systematic review was conducted using Medline, Web of Science, Scopus, Cinahl, ProQuest and Lilacs, with the search terms “laughter”, “laughter therapy”, “fertilization in vitro” and “fertilization”. Intervention studies published in English, Spanish, or Portuguese were included, with no limits on the date of publication. Studies with other designs, those conducted with animals and grey literature were excluded. The quality of the included studies was assessed using the Joanna Briggs Institute critical appraisal tools. Results: In total, n = 3 studies (1 randomized clinical trial and 2 quasi-experimental) were included, evaluating pregnancy rates and symptoms of depression and anxiety. The interventions included clowns performing magic tricks and interpreting comic situations. Additionally, they incorporated hand clapping, breathing exercises, childlike playfulness, drinking milk, muscle relaxation exercises, candles, and music. Conclusions: This review does not provide clear evidence on the effectiveness of laughter therapy in increasing pregnancy success in IVF. Although it may have some positive effects in reducing symptoms of depression and anxiety, it is important to note that while the reduction of these symptoms may enhance the emotional well-being of patients, it has not been demonstrated to directly lead to an increase in pregnancy rates. Laughter therapy is an innovative, non-pharmacological intervention that is simple, non-invasive, easy to implement and cost-effective; however, the number of available studies is insufficient. More research is needed to provide better and higher-quality evidence using rigorous designs to evaluate this intervention in IVF clinical practice.