Bioimaging enables the visualisation of biological processes at the microscopic and macroscopic levels, finding applications from cellular tracking to whole body scanning for diagnosis purposes. The different techniques developed to acquire images make use of most radiation types of the electromagnetic spectrum. Recently, there has been interest in non-ionising radiation imaging techniques that can offer improved detection or additional information about biological processes, and fluorescence and photoacoustic imaging have become an eminent field. Conjugated polymers are versatile materials for bioimaging due to their tailored absorption and emission spectra and applications in both fluorescence and photoacoustic imaging. This review gives an overview on bioimaging techniques, with a special focus on conjugated polymer nanoparticles (CPNs), the different types of nanoparticle chemistries published and their preclinical safety assessment.