On 13 May 2005, it was announced that Foulkes was to receive a life peerage.
On 16 June 2005, he was created Baron Foulkes of Cumnock, of Cumnock in East Ayrshire.

Foulkes was a member of the Intelligence and Security Committee in the Cabinet Office from 2007 to 2010.
Since October 2010, he has been a member of the Joint Committee on National Security Strategy.
He serves on the Executive Committee of the Inter-Parliamentary Union and the Board of Governors of the Westminster Foundation for Democracy.
Since March 2011, he has been a member of the Lords EU Select Committee and Lords EU Sub Committee on Social Policy and Consumer Protection.

Foulkes is very active on Caribbean matters, serving as president of the Caribbean Council, chair of the Belize and Dominican Republic All-Party Parliamentary Groups (APPGs), and vice-chair of the Trinidad and Tobago and British–Central America APPGs.
He is also a member of Labour Friends of Israel.

In April 2008, Foulkes was criticised for his expenses claims, which included around £45,000 over a period of two years for overnight subsistence to stay in a flat he had inherited.
Between April 2007 and March 2008, he claimed £54,527 in expenses from the House of Lords but, in January 2009, was shown to have one of the lowest expenses claims in the Scottish Parliament.
During the 2009 expenses controversy, he attacked media presenters in an exchange with the BBC's Carrie Gracie.
He said some presenters, such as Jeremy Paxman and John Humphrys, were being paid to "sneer at democracy and undermine democracy".
However, in August 2009, Foulkes made a series of Freedom of Information requests about the expenses of retiring British Army head General Sir Richard Dannatt.
He was accused by Shadow Defence Secretary Liam Fox of leading a New Labour smear campaign.

Foulkes was one of the fifty signatories to a letter published in the Guardian in 2010, which called for Pope Benedict XVI not to be given a state visit to the UK, and accused the Catholic Church of increasing the spread of Aids and promoting segregated education.
On 24 August 2011, The Scotsman reported that he had announced he would table an amendment to the Scotland Bill with the intention to make it impossible for the Scottish Government to sustain free university education for students in Scotland.
On 2 February 2012, he tabled a motion calling for the Scottish independence referendum to contain no extra question on increased devolution, and proposing a separate referendum be held on the subject in the event independence were rejected and Scotland voted to stay in the UK.

Foulkes in July 2019 was among 67 Labour peers to lend their names to an unauthorised advertisement in The Guardian which criticised Jeremy Corbyn for failing to effectively tackle antisemitism in the party.
Later, in the August, Foulkes said Richard Leonard and Lesley Laird should resign as Leader and Deputy Leader of the Scottish Labour Party respectively, accusing Leonard of having "no charisma and no leadership credentials" and saying "almost anyone would be better" than Laird.
He repeated calls for Leonard to resign in July 2020.
On 13 May 2005, it was announced that Foulkes was to receive a life peerage. On 16 June 2005, he was created Baron Foulkes of Cumnock, of Cumnock in East Ayrshire.
Foulkes was a member of the Intelligence and Security Committee in the Cabinet Office from 2007 to 2010. Since October 2010, he has been a member of the Joint Committee on National Security Strategy. He serves on the Executive Committee of the Inter-Parliamentary Union and the Board of Governors of the Westminster Foundation for Democracy. Since March 2011, he has been a member of the Lords EU Select Committee and Lords EU Sub Committee on Social Policy and Consumer Protection.
Foulkes is very active on Caribbean matters, serving as president of the Caribbean Council, chair of the Belize and Dominican Republic All-Party Parliamentary Groups (APPGs), and vice-chair of the Trinidad and Tobago and British–Central America APPGs. He is also a member of Labour Friends of Israel.
In April 2008, Foulkes was criticised for his expenses claims, which included around £45,000 over a period of two years for overnight subsistence to stay in a flat he had inherited. Between April 2007 and March 2008, he claimed £54,527 in expenses from the House of Lords but, in January 2009, was shown to have one of the lowest expenses claims in the Scottish Parliament. During the 2009 expenses controversy, he attacked media presenters in an exchange with the BBC's Carrie Gracie. He said some presenters, such as Jeremy Paxman and John Humphrys, were being paid to "sneer at democracy and undermine democracy". However, in August 2009, Foulkes made a series of Freedom of Information requests about the expenses of retiring British Army head General Sir Richard Dannatt. He was accused by Shadow Defence Secretary Liam Fox of leading a New Labour smear campaign.
Foulkes was one of the fifty signatories to a letter published in the Guardian in 2010, which called for Pope Benedict XVI not to be given a state visit to the UK, and accused the Catholic Church of increasing the spread of Aids and promoting segregated education. On 24 August 2011, The Scotsman reported that he had announced he would table an amendment to the Scotland Bill with the intention to make it impossible for the Scottish Government to sustain free university education for students in Scotland. On 2 February 2012, he tabled a motion calling for the Scottish independence referendum to contain no extra question on increased devolution, and proposing a separate referendum be held on the subject in the event independence were rejected and Scotland voted to stay in the UK.
Foulkes in July 2019 was among 67 Labour peers to lend their names to an unauthorised advertisement in The Guardian which criticised Jeremy Corbyn for failing to effectively tackle antisemitism in the party. Later, in the August, Foulkes said Richard Leonard and Lesley Laird should resign as Leader and Deputy Leader of the Scottish Labour Party respectively, accusing Leonard of having "no charisma and no leadership credentials" and saying "almost anyone would be better" than Laird. He repeated calls for Leonard to resign in July 2020.
George Foulkes, Baron Foulkes of Cumnock