In February 2011 Souter again pledged financial support for the SNP, promising to match every pound they raised with a donation of up to £500,000. Announcing his support he said Salmond and the SNP deserved a second term in office. The SNP won a resounding victory in the election with Salmond being returned unopposed as First Minister.
In 2011 he was presented with an outstanding achievement award at the 2011 Perthshire Chamber of Commerce Business Star Awards.
Souter was knighted in the 2011 Birthday Honours for services to transport and the voluntary sector. This proved controversial, and was criticised by Scottish Labour MP Cathy Jamieson, who suggested a link between the knighthood and the large amounts of money he has donated to the Scottish National Party. In a public statement, Jamieson said: "The First Minister and his party must look seriously at the relationship they have developed with wealthy individuals handing them large sums of cash. The public will rightly be asking what's next on Mr Souter's shopping list?" Salmond denied any wrongdoing in the matter and referred himself for investigation after calls for a probe by Scottish MP Jim Sheridan. An independent report, conducted by Lord Fraser of Carmyllie, cleared Salmond of any wrongdoing, asserting that "There appears to me to have been no breach of the ministerial code by Alex Salmond as First Minister and he should be wholly exonerated of any breach."