About 140 search warrants were issued by some 40 forces during the UK-wide raids, led by the Child Exploitation and Online Protection Centre.
Most warrants related to downloading and sharing indecent images.
Some 80 children were removed from harm, including 20 found at raided properties.
Operation Tharsley took place over 48 hours on Tuesday and Wednesday, with support from the Serious Organised Crime Agency (Soca).
Those arrested include a pathologist, a firefighter, an activities instructor, government employees, and a referee.
Known offenders who had breached the conditions of the sex offenders register were also held.
Forty-two forces from around the UK made the following arrests:
Officers seized laptop computers, USB storage devices, and digital cameras, according to Ceop's deputy chief executive, Andy Baker.
Mr Baker said pictures would be scrutinised to see identify victims using clues in the background.
"Every image is a crime scene," he added.
Meanwhile,  
          Ceop published a report
 on risks posed by people who download indecent images of children.
It reported a correlation between the viewing of abusive images and sex attacks being committed against children.
Principal analyst at Ceop, Kate Fisher, said abusive internet images were becoming "more extreme, sadistic and violent, and feature increasingly younger children".
Ceop called for police to prioritise investigating suspects who had easy access to children.
Christian Sjoberg of NetClean, which aims to prevent child sexual abuse content, said: "As police cuts hit home and case volumes increase, crime-fighting agents attempting to tackle the problem are finding their resources stretched."
"Sophisticated internet use makes the job of child protection increasingly complex, but technology can also hold the key to finding and preventing those who create and distribute this kind of material."
The raids come as the UK government announces a draft bill to allow details of internet use to be stored for a year, enabling intelligence services to track crime with modern technology.
Home Secretary Theresa May said: "Communications data is vital for the police in their fight against crime, including serious offences such as child abuse, drug dealing and terrorism."
A retired teacher, members of the armed forces and a scout leader are among 99 people arrested in raids targeting online paedophiles.