The Blantyre ward by-election was caused by the death of Labour councillor Jim Handibode in September.
Labour's Mo Razzaq held the seat with 47.2% of the first-preference votes, down from 54.3% in 2012 when four seats were up for election.
The first-count voting saw Labour receive 1,476 votes, with the SNP on 1,236.
The Conservatives received 140 votes, the SSP 122, Liberal Democrats 92 and UKIP 59.
The turnout was 24.3% from a total electorate of 13,047.
South Lanarkshire Council is currently run by a Labour administration.
Labour has held a South Lanarkshire Council seat in a by-election despite an 8% swing from the party to the SNP.