The nutritional status of reproductive-aged couples can have a significant impact on fertility status, but the effect of dietary patterns on pregnancy outcomes in people using Assisted Reproductive Technologies (ART) is currently unknown. This review aimed to synthesize the published research investigating the relationship between preconception dietary patterns and clinical pregnancy or live birth in men and women of reproductive age undergoing ART. Six electronic databases were systematically searched for original research published between January 1978 and June 2021. Original research reporting on the effect of pre-defined dietary patterns on either clinical pregnancy and/or live birth rates following in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) in men and women aged 18-49 years were eligible for inclusion. Studies were assessed for risk of bias according to the Cochrane guidelines. Included studies underwent qualitative and quantitative synthesis using random-effects model meta-analyses. Thirteen studies (12 cohort studies, 1 RCT) reporting on 3638 participants (93% female) were included in the review. All studies had a moderate-high risk of bias. In individual studies, maternal adherence to four dietary patterns [Mediterranean diet (RR: 1.22; 95% CI: 1.05, 1.43), novel profertility diet (OR: 1.43; 95% CI: 1.19, 1.72), Iranian traditional medicine diet (OR: 3.9; 95% CI: 1.2, 12.8), Dutch National dietary recommendations diet (OR: 1.65; 95% CI: 1.08, 2.52)] were associated with increased likelihood of achieving a clinical pregnancy, while two dietary patterns [novel profertility diet (OR: 1.53; 95% CI: 1.26, 1.85), Mediterranean diet (RR: 1.25; 95% CI: 1.07, 1.45)] were associated with increased probability of live birth. Meta-analyses showed an association between adherence to the Mediterranean dietary pattern and live birth across two studies (OR: 1.98; 95% CI: 1.17, 3.35; I2 = 29%, n = 355), but no association with clinical pregnancy. As the relationship between dietary patterns and ART outcomes is currently inconsistent, higher quality nutrition research is required to further explore this emerging field of interest (PROSPERO registration: CRD42020188194).