This work studies the structural, microstructural, and magnetic properties of carbon nanotubes with magnetic iron carbide nanoparticles attached to their walls. The samples were fabricated in a single step using a modified chemical vapor deposition (CVD) method. The proposed method allows to obtain carbon nanotubes with iron carbide nanoparticles partially immersed in their walls. The carbon nanotubes were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Results show that the obtained carbon nanotubes are multi-walled with a bamboo-like structure. They have an average diameter of 40 nm and inner cavities of 20 nm in diameter. The magnetic nanoparticles are firmly fixed to the nanotubes, and they have an average diameter of 15 nm with rounded borders. The iron carbide nanoparticles exhibit a ferromagnetic behavior with high magnetic saturation resulting from their morphological characteristics and their location on the walls of the nanotubes, which prevent their agglomeration and reduce dipolar interactions.