The filling of single-walled carbon nanotubes (SWCNTs) is a promising method for controlling the properties of SWCNTs for applications. Filling of SWCNTs with metal halides, metal chalcogenides, metals, and metallocenes is performed. Metal halides are a large group of filling substances with large work functions. Filling of the SWCNTs with metal halides leads to p-doping of the SWCNTs. Metal chalcogenides can lead to p-doping of the SWCNTs, too. Metals with low work functions result in n-doping of the SWCNTs. Filling of the SWCNTs with metallocenes with further annealing leads to variations in the doping types of the SWCNTs. The electronic properties of the filled SWCNTs are important for nanoelectronics, electrochemical energy storage, and biomedical applications. SWCNTs filled with various substances with tailored electronic properties can be applied in those fields. The electronic properties of the filled SWCNTs are influenced by the structure of the filled material. The structure of the filled materials defines their band structure. In SWCNTs with different diameters, various structures of the filled materials are obtained. This influences the electronic properties of the filled SWCNTs. Here, the structure and electronic properties of cobalt bromide-filled SWCNTs are investigated. Using high-resolution transmission electron microscopy and Raman spectroscopy, we reveal the properties of the filled SWCNTs. Novel structures of cobalt bromide-filled SWCNTs with large p-doping are observed. The obtained data are important for various uses of the filled SWCNTs.