The aim is to prevent new sex offences from being committed
Sex offenders will be made to take lie detector tests as part of probation conditions when they are freed from prison, the Ministry of Justice says.
A three-year pilot project in East and West Midlands will aim to establish whether polygraph testing should be introduced across England and Wales.
About 25 sex offenders will initially take part, starting on Wednesday.
The idea was first piloted in 2003 with voluntary testing of offenders, which prompted admissions in 80% of cases.
In that pilot 90% of probation officers said the testing of offenders was helpful in assessing the risks they pose to the public.
Between 350 and 450 offenders are expected to be tested over the three-year period of the latest pilot scheme. Those who refuse risk being sent back to prison.
Sex offenders will be chosen by their probation officer, who will consult other professionals, to decide whether a polygraph condition should be included in the offender's licence.
Professor Don Grubin, who will carry out the tests, said the aim of this and other measures was to prevent new sex offences from being committed.
"Disclosures made during polygraph examinations, as well as conclusions drawn from passed or failed examinations, allow probation officers and the police to intervene to reduce risk," he said.
"Just as important, it is also aimed at enhancing the co-operation of offenders with supervision, helping them to focus on, and avoid, the sorts of behaviours that make re-offending more likely."
Claude Knights, director of the children's charity Kidscape, said she believed the tests could help to assess risk.
"I'm hoping that this will be an incentive for paedophiles to disclose more information, which would help us to manage their release more effectively."
Justice Minister David Hanson said the use of thorough systems to ensure a "high level vigilance" of serious sexual and violent offenders after their release from prison was vital for protecting communities.
The long-expected move had been a commitment of the government, he said, and he was "proud to say that this can now legally happen from Wednesday".
Each polygraph session will take between 90 minutes and two hours and will consist of three phases.
In a pre-test interview the subject will be told the questions they are to be asked so they can make any relevant disclosures beforehand.
They will then be attached to the polygraph machine and asked the questions.
Thirdly the polygraph operator will interpret the responses and, in a final interview, the subject will be told the results of the test and asked to explain any failures.
Pam Hibbert, assistant director of policy at children's charity Barnardos, said the tests would "increase public confidence" that sex offenders were complying with supervision, staying away from schools and playgrounds and living and sleeping where they are supposed to.
"It is important however that this is used as part of a package of measures including greater use of satellite tracking."
She said that would be more "false comfort of Sarah's Law", which in four pilot areas allows parents to ask police if anyone with access to children has convictions for child sex offences.