Tony Blair did not deem child sexual abuse allegations a reason to prevent Lord Janner, the former Labour MP, receiving a peerage, an inquiry heard.
Lord Janner died in 2015 under suspicion of 22 counts of child sexual abuse dating back to the Sixties.
The long-serving politician always denied the allegations made by Frank Beck, a care home boss accused of sexual and physical assaults on dozens of children, during his 1991 abuse trial.
Beck was jailed for life and died in prison three years later, while Lord Janner was not charged until 2015. Yesterday Mr Blair said he "would have known" about the claims made against Lord Janner when putting his name forward for a peerage in 1997, weeks after he swept to power.
But the former prime minister told the Independent Inquiry into Child Sexual Abuse he was also aware that the allegations had been investigated by police and that Lord Janner "vigorously denied" them.
Lord Janner was made a peer shortly after stepping down as an MP for Leicester West.
In a statement read to the inquiry yesterday, Mr Blair said: "In 1997 I would have known of the allegations made in 1991 in respect of Lord Janner by Frank Beck during his trial.
"As regards the nomination, I would expect such allegations to be considered (by the Political Honours Scrutiny Committee) as part of that process.
"In the circumstances of Lord Janner's vigorous public denial, a police investigation, and charges not being brought, I do not believe the allegations would have been investigated further beyond confirming those facts, nor that I would have considered them a bar to the nomination.
"At this distance, I am unable to specifically identify any particular failing or shortcoming that I was personally responsible for in my capacity as leader of the Labour Party or as prime minister."
Mr Blair was unable to be questioned on his evidence as the statement was read during a closed session to protect the anonymity of sexual abuse complainants.
IICSA also heard that Downing Street wrote to the Home Office in July 1992 saying it had received a recommendation for Lord Janner to be included in a future Honours list - a proposal the Home Office did not have any concerns over, despite the link to Beck.
The Downing Street letter stated the recommendation for Lord Janner to be honoured was "presumably for a knighthood to recognise his services to the Jewish community in Britain".
Helen Ewen, from the Cabinet Office department involved in the honours process, told the inquiry that the Home Office appeared "supportive" of the recommendation but that Lord Janner did not receive the honour.
She said: "The Home Office, I think, replied to indicate they had no objection, they found no adverse reason not to proceed, but no honour was given in the end."
There was no evidence to suggest why the recommendation was not pursued, the inquiry heard.