The count took place at Hammersmith Town Hall with results announced in the early hours of Friday morning (May 8).
Mr Slaughter won with 23,981 votes, beating Conservative candidate Charlie Dewhirst (17,463 votes) into second place, and extending his 2010 majority from 3,549 to 6,518.
Lib Dems clung on to third ahead of the Greens and UKIP, while Independent candidate Stephan Brennan received just 82 votes.
In his victory speech, Mr Slaughter thanked the electorate and pledged to rededicate himself to them over the next five year.
He said: “When we talk to people we talk to them in a language that means something about issued that mean something.”
He attacked NHS plans for north-west London and called on a proper health service in the borough.
With results elsewhere in the country showing a good night for the Conservatives, Mr Dewhirst said: “We have lost the battle but won the war.”
Speaking before the results were declared, Mr Slaughter told getwestlondon: “I have done my best and the result will take care of itself. I have done my best to represent the people of Hammersmith for 10 years an an MP and 30 years as a councillor.
“I hope the people will stick with me and trust that I’m doing the best I can for them and their families.”