This study aims to assess potential complications and effects on the magnetic resonance imaging (MRI) image quality of a new MRI-conditional breast tissue expander (Motiva Flora®) in its first in-human multi-case application. Twenty-four patients with 36 expanders underwent non-contrast breast MRI with T1-weighted, T2-weighted, and diffusion-weighted imaging (DWI) sequences on a 3 T unit before breast tissue expander exchange surgery, being monitored during and after MRI for potential complications. Three board-certified breast radiologists blindly and independently reviewed image quality using a four-level scale (“poor”, “sufficient”, “good”, and “excellent”), with inter-reader reliability being assessed with Kendall’s τb. The maximum diameters of RFID-related artifacts on T1-weighted and DWI sequences were compared with the Wilcoxon signed-rank test. All 24 examinations were completed without patient-related or device-related complications. The T1-weighted and T2-weighted sequences of all the examinations had “excellent” image quality and a median 11 mm (IQR 9–12 mm) RFID artifact maximum diameter, significantly lower (p< 0.001) than on the DWI images (median 32.5 mm, IQR 28.5–34.5 mm). DWI quality was rated at least “good” in 63% of the examinations, with strong inter-reader reliability (Kendall’s τb0.837, 95% CI 0.687–0.952). This first in-human study confirms the MRI-conditional profile of this new expander, which does not affect the image quality of T1-weighted and T2-weighted sequences and moderately affects DWI quality.