Emma Henlan was elected in the poll by a majority of 176 votes, ahead of Labour's Rob Hevican.
It means the Tories now have 10 seats on Sandwell Council, having had none ahead of the local elections in May.
The by-election had been called after Mr Hevican's wife, Sandra Hevican, died from Covid earlier this year, having served as a councillor in the ward since 2014.
Turnout at the election was 20.13 per cent.
The result leaves Labour with 59 seats, while the Conservatives have 10 and there are three independent councillors.
More to follow.