In this paper, we investigate the structure and thermal properties of aluminum-rich transparent Ca–Al–Si–O–N glasses. The obtained glasses were prepared by a traditional melt-quenching technique at 1650 °C using AlN as the nitrogen source. The obtained glasses have a nAl/nSi>1 and contain up to 17 eq.% of N. The structure of the glasses was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, infrared, and Raman spectroscopy techniques. The structure analysis shows a higher preference for Si–N bond formation relative to Al–N bond formation and aluminum is predominately present in tetrahedral coordination as AlO4 units. The thermal properties of samples were studied by differential thermal analysis and the obtained glass transition temperature ranges from 875 °C to 950 °C, and is primarily influenced by the N content. The glass stability can be correlated with both the N and Al contents in the studied glasses. It is improved due to the increased degree of network polymerization by the incorporation of nitrogen.