David Martin Nappin, 38, breached his sexual harm prevention order when an unregistered phone was found in his hostel room in Blackburn.
It contained 2,209 indecent images, including 802 Category A photos – the most serious examples of child sexual abuse.
"The images in this case were described as harrowing,” Robert Richards, from the East Management of Sexual and Violent Offender Team (MOSOVO), said.
“Nappin by his own admission, not only wishes to view indecent images, but to also act on those desires.
“[He] presents a very high risk of serious harm to female children under 10.”
Nappin was released on licence following a previous prison sentence on July 30, 2020.
As part of the sentence, Nappin was subject to a 10-year sexual harm prevention order which limited his contact with children and use of the internet.
He was also made subject to a notification requirement.
Those requirements meant he had to declare any device capable of accessing the internet.
On November 10, 2020, officers were contacted by staff at a probation hostel in Blackburn who reported finding an unregistered phone in the defendant’s room.
Nappin had also sent the hostel manager a message on his registered mobile phone which read: “You'll find something, the stuff that got me in trouble last time.”
Officers from the MOSOVO unit attended Nappin’s place of work the same day to arrest him and seize his registered and unregistered mobile phones.
Police found 2,209 indecent images including 802 Category A, 491 Category B and 898 Category C images of children.
The phone also contained another eight prohibited images and ten extreme pornographic images.
Mr Richards added: “Nappin was sentenced to serve two years and six months in prison to be followed by an extended licence of seven years.
“He will continue to be subject to sex offender notification requirements and a revised sexual harm prevention order indefinitely.
“Lancashire Police are committed to bringing to justice, those who commit crimes against the most vulnerable in our society, and will work tirelessly to keep children safe from sexual predators.”