Breast cancer is the most common cancer globally, and mastectomy rates are increasing. Tissue expander-based breast reconstruction is used when direct-to-implant methods are unsuitable. A novel magnetic resonance imaging compatible breast tissue expander has recently been introduced. This study aims to evaluate its clinical use in pre-pectoral breast reconstruction and its complication profile. A monocentric prospective cohort study included women undergoing expander-based breast reconstruction after mastectomy with the new tissue expander between August 2020 and October 2024. The expanders were placed in a pre-pectoral plane with optional use of acellular dermal matrices in selected cases. Demographic data, comorbidities, and surgical details were analyzed. Tissue expander-independent and -dependent complications were assessed. A total of 200 tissue expanders were implanted in 146 patients (92 unilateral, 54 bilateral). Major complications requiring expander replacement included infection (3.0%), partial necrosis of the mastectomy flap (2.5%), wound dehiscence (1.0%), hematoma (1.0%), and seroma (0.5%). Tissue expander rotation and/or flipping, as well as iatrogenic rupture, occurred in 2% and 3.5% of all cases. Definitive removal was required in ten cases, mainly due to mastectomy flap necrosis and wound dehiscence with or without expander exposure (2.5%), as well as infection (2.0%). The new breast tissue expander features a biocompatible surface that does not adhere to adjacent tissues and therefore needs fixation alongside the inframammary fold, particularly if used in the pre-pectoral plane, contributing to a low complication rate. While short-term results are promising, long-term follow-up on a larger scale is needed to confirm these outcomes.