The Local Government by-election for the Armadale and Blackridge council ward was held on Thursday last week.
The by-election was conducted under the Single Transferable Vote (STV) system, a form of proportional representation.
Sarah King, the Scottish National Party candidate, was declared the newly-elected member for the Armadale and Blackridge council ward.
She said: “I am very pleased to have been elected to represent the people of Armadale, Blackridge, Torphichen and Westfield.
“I pledge to always put the interests of local people first and to be a strong voice for our community.
“This strong result is also a major boost for the SNP as we approach May’s General Election and shows people across West Lothian are turning away from a Labour party which has abandoned its principles and is committed to George Osborne’s plans for a further £30billion of cuts.
“People are putting their faith in the SNP to make Scotland’s voice heard.”
Total electorate eligible to vote 123,15; ballot papers returned were 3776 based on a turnout of 30.7 per cent. Total papers rejected were 46.