Genetically engineered mouse models (GEMMs) are instrumental for modelling local and systemic features of complex diseases such as cancer. Non-invasive, longitudinal cell detection and monitoring in tumors, metastases and/or the micro-environment is paramount to achieve a better spatiotemporal understanding of cancer progression and to evaluate therapies in preclinical studies. Bioluminescent and fluorescent reporters marking tumor cells or their microenvironment are valuable for non-invasive cell detection and monitoring in vivo. Here we report the generation of a dual reporter allele allowing simultaneous bioluminescent and fluorescent detection of cells that have undergone Cre-mediated recombination in mice. The single copy knock-in allele in the permissive Collagen I locus was evaluated in the context of several cancer GEMMs, where Cre expression was achieved genetically or by ectopic virus-mediated delivery. The new reporter allele was also combined with popular gene-targeted alleles used in bone, prostate, brain and pancreas cancer research, as well as with alleles inserted into the commonly used Rosa26 and Collagen I loci. This allele is therefore a useful addition to the portfolio of reporters to help advance preclinical research.