Former News of the World royal editor Clive Goodman hacked Kate Middleton's phone 155 times and Prince William's mobile on 35 occasions, the Old Bailey heard.
Goodman, who returned to the witness box after weeks of ill health, was also accused of hacking Prince Harry's phone nine times.
Kate was even hacked on Christmas Day in 2005, jurors heard.
The former royal editor was accused of being more heavily involved in phone hacking in 2005 and 2006 with private detective Glenn Mulcaire than had been previously heard.
Goodman and Mulcaire were convicted in 2006 of hacking phones in relation to royal aides.