Objective: Emotion regulation (ER) difficulties are frequently reported in individuals with Functional Neurological Disorder (FND), yet most evidence derives from self-report data, and little is known about intra- and interpersonal ER preference and success under controlled conditions. Methods: In a multimethod design, Study 1 assessed habitual ER difficulties and interpersonal ER using validated questionnaires in 109 individuals with FND and 88 healthy controls (HC). Study 2 employed two laboratory paradigms in 33 individuals with FND and 33 HC, examining ER choice and ER success during intrapersonal (reappraisal vs. distraction) and interpersonal regulation (self- vs. other-guided reappraisal). ER success was indexed by subjective arousal ratings and startle reflex magnitude. Results: In Study 1, individuals with FND reported greater ER difficulties, higher alexithymia, more childhood trauma, and reduced use of interpersonal ER compared to HC. In Study 2A, stimulus intensity predicted ER choice, with a shift toward distraction at higher intensities; groups did not differ in intrapersonal ER choice or success. In Study 2B, individuals with FND showed a non-significant trend toward reduced preference for interpersonal regulation. Interpersonal reappraisal was associated with lower startle amplitudes than intrapersonal reappraisal, indicating stronger physiological downregulation. Across paradigms, ER success did not significantly differ between groups. Conclusions: FND is characterized by pronounced self-reported intra- and interpersonal ER difficulties, whereas laboratory findings suggest preserved momentary ER implementation. Interpersonal ER may represent a clinically relevant domain in FND, warranting replication in adequately powered samples. Registration: Preregistered at the Open Science Framework (https://osf.io/hxfje).