The veteran politician, who spent 43 years as an MP, died last month aged 84 following a short illness.
The Red Flag was played on the organ as political figures past and present filed into St Michael's Parish Church in Linlithgow.
Mr Dalyell's body was donated to science in line with his wishes, followed by a private interment.
Tributes were led by former Labour MP Brian Wilson, who spoke of Mr Dalyell's commitment to his constituents and party.
Mr Wilson said: "Tam never lost sight of the things that brought him into politics. There wasn't a subject you could not go to him for advice."
He later said he "would miss Tam's phone calls" and described him was a "great man with great influence".
Labour colleagues at the service included former chancellor Alistair Darling and former MPs Jim Murphy, Ian Davidson and Margaret Curran.
Scottish Secretary David Mundell also attended as well as SNP minister Fiona Hyslop.
The Old Etonian baronet was elected to represent West Lothian in 1962. He became MP for Linlithgow 21 years later and was named Father of the House, the longest continuously serving MP, in 2001.
A fervent opponent of Scottish devolution, Mr Dalyell's famous constitutional challenge, "Why should Scottish MPs at Westminster be able to vote on English matters when English MPs would be unable to vote on Scottish issues," became known as the "West Lothian question".
A further memorial service is planned for London.
A memorial service has been held for former Labour MP Tam Dalyell.