An independent national review will identify the lessons to be learned from Arthur's death, in June last year, for the benefit of other children elsewhere in England.
The government has also commissioned an urgent inspection of social care, health, police and probation services in Solihull to whom Arthur was known, in an effective upgrading of an existing local review.
Tustin was sentenced to a minimum 29 years in prison for Arthur's murder, while Hughes was jailed for 21 years for manslaughter after encouraging the killing of his son.
The Attorney General's Office (AGO) this weekend confirmed Tustin and Hughes' sentences are to be reviewed.
On Sunday, crowds of people brought the Solihull street where Arthur lived to a standstill as they held a vigil for him.
They released blue balloons – the colour of his football team Birmingham City FC – and broke out into applause.
Families, including children, laid flowers and toys outside the six-year-old's home.
Footballers across the country are also paying tribute to Arthur for a second day.
Teams – including Manchester United during their game against Crystal Palace – asking fans to clap for him in the sixth minute of matches.
Arthur was left with an unsurvivable brain injury while in the sole care of Tustin, with the boy's body also covered in 130 bruises.
Speaking to Sky News about the case, Mr Raab, who is also justice secretary and is a father of two young boys, said he “can't begin to imagine how anyone could be that cruel”.
“There will be a local safeguarding review which will look at the local authority's actions – whether any lessons could have been picked up earlier, whether any warning flags could have been put up earlier,” he told the Trevor Phillips On Sunday show.
“And the prime minister has made clear, as well as that, we want to see how social services and the local authorities liaise with the criminal justice agencies and what lessons further we can learn.”
Education Secretary Nadhim Zahawi, who is due to make a House of Commons statement on Arthur's case on Monday, said the government would “not rest until we have the answers we need”.
“We are determined to protect children from harm and where concerns are raised we will not hesitate to take urgent and robust action,” he added.
Mr Zahawi said he had asked Annie Hudson, the chair of the Child Safeguarding Practice Review Panel, to work with officials in Solihull to deliver a national review due to “the enormity of this case, the range of agencies involved and the potential for its implications to be felt nationally”.
The Sunday Times reported the action being taken after Arthur's death would be expected to consider whether to introduce safeguarding guidelines for at-risk children should there be future national lockdowns.
Mr Raab told Sky News there were “multi-dimensions” to cases of child cruelty, including the “callous” actions of perpetrators, as well as the response of local authorities and the “incredible job” done by social workers on the front line.
“As part of the pandemic response, we've invested close to £5bn in giving local authorities the support they need,” he said.
“One of the things we know about lockdown, whilst lots of families enjoy having more time together, for those who are the victims of domestic abuse, it has been a very serious time and some of those risks have been magnified.”Internet Explorer Channel Network