The doodle depicts the Lion Rampant, the royal emblem of Scotland, forming the letter 'e' of Google, with all the other letters being made of stone, surrounded by thistles.
Saint Andrew was a fisherman and a disciple of Jesus, who spread the new Christian faith throughout Asia Minor and Greece.
He was crucified by the Romans in Greece in the 1st century AD on an X shaped cross, which leant its diagonal form to the Cross of St Andrew, seen on the Scottish flag, or Saltire.
Alongside Scotland, St Andrew is the patron saint of fishmongers, singers, maidens and women wanting to become mothers.
Marking St Andrew's Day, prime minister David Cameron said that Scotland was "a small country with a big heart and a big voice".
"For centuries, Scotland's greatest asset and greatest export has been its people," he said.
"Scots have helped bring peace and security to nations, made some of the world's greatest inventions and been at the forefront of international trade in every continent."