High performance carbon nanotube fibres and yarns with similar strength to Kevlar could now offer significant structural reinforcement and multifunctionality to 3D printed parts. However, recently printed parts which were reinforced with highly-densified CNT yarns exhibited only modest mechanical properties due to poor wettability with polymers. In this work, PMMA is proposed for infiltration of CNT fibres produced via Floating Catalyst CVD, as the polymer may be printed at a lower temperature and is industrially used in resilient fibre-reinforced thermoplastic prepregs and laminates. Nanoscale chemical imaging by AFM combined infrared spectroscopy revealed good infiltration while the PMMA/CNT fibre composite filaments exhibited pronounced increase in tensile strength and Young’s modulus.