The 27-year-old Scot pulled out of a planned performance at the O2 Arena in London on Thursday, as well as Friday's gig at the Motorpoint Arena in Cardiff.
Nutini - whose third album Caustic Love topped the charts earlier this year - postponed two concerts in Glasgow this week on medical advice.
Fans with tickets should keep them and look out for the rescheduled dates.
A statement announcing the latest postponements said: "Regrettably Paolo Nutini is suffering with severe tonsillitis and is not well enough to perform."
It also offered an apology for the "inconvenience and disappointment" caused.
Chart-topping singer Paolo Nutini has postponed a two more UK arena shows due to "severe tonsillitis".