Development of novel analytical devices complying with modern requirements of simplicity and cost-effectiveness is an important task. Multisensor systems based on various types of chemical sensors are promising tools in this respect. Herein the development of a new approach to design of optical multisensor systems is reported. The idea is to use a combination of molecular emitters – cyclometalated Ir(III) compounds – as tuneable multiband light sources. Upon the 365 nm light irradiation these compounds emit in certain wavelength ranges, that can be tuned by changing of ligand environment of Ir(III). This gives an option to choose an appropriate set of emitters for particular analytical tasks, thus giving the way for construction of novel type of optical multisensor systems with tuneable emittance. The multiband light illuminates the analyzed sample in the specific range of wavelengths with consequent registration of sample absorption spectra. Chemometric processing of the resulted signals allows quantification of particular analytes in mixtures. The details of the system design and its’ performance validation in complex aqueous mixtures of metal ions (cobalt, nickel and copper) are described in this paper. It is shown that precise quantitative analysis of all three ions simultaneously is possible with root mean-square errors in prediction below 0.007 M in the range 0.01–0.1 M. We believe that this approach gives a wide variety of options for real-world applications.