Underground bolometric experiments offer unique opportunities for the study of neutrino-less double beta decay and other rare decays. Both the current and next generation detectors consist of large arrays of macro-bolometers. In particular, CUORE is the first bolometric experiment reaching the 1-ton scale and has successfully completed the first physics run. CUPID, CUORE upgrade with particle identification, has also started its first demonstrator (CUPID-0), with very promising performance. The readout of such large scale and high sensitivity bolometric detectors poses new challenges for the front-end and detector calibration electronic systems. We will present the strategies, design choices and actual performance of the electronic instrumentation as implemented in CUORE and CUPID-0.