(1) Background: Eustachian tube dysfunction (ETD) is a frequently observed clinical manifestation of chronic rhinosinusitis (CRS). This systematic review aimed to evaluate the function of the Eustachian tube following endoscopic sinus surgery (ESS) in adult CRS patients with confirmed preoperative ETD symptoms. (2) Methods: A systematic search of PubMed, Cochrane, Embase, and MEDLINE electronic databases was conducted. The review was performed following the PRISMA guidelines. Studies investigating concurrent ETD in CRS patients who underwent ESS were retrieved. The changes in ETD outcomes were measured by the 7-item Eustachian Tube Dysfunction Questionnaire (ETDQ-7). We employed a random-effects model to conduct the meta-analysis (3) Results: We included seven observational studies that involved a total of 436 CRS patients with concurrent ETD. The pooled results revealed a statistically significant reduction (Standardized mean difference = −1.24; 95% CI = −1.64 to −0.84) in ETDQ-7 scores among the CRS with ETD patient cohort at the 3-month postoperative follow-up. (4) Conclusions: ESS serves as an effective intervention for improving E-tube function in adult CRS patients with concurrent ETD. Future prospective randomized controlled trials that incorporate various outcome predictors should be conducted to explore potential clinical factors for greater ETD improvement and normalization after ESS.