Jake Morrison triumphed over Lord Storey in Wavertree as the Liberal Democrats - who held power only two years ago - took heavy losses.
Another high profile Lib Dem casualty was former education spokesman Paul Clein, who said his defeat was not "a reflection on local candidates".
Labour took 12 of the 14 Lib Dem seats being contested.
Mr Morrison, a healthcare assistant at the Royal Liverpool Hospital, said: "It's absolutely fantastic - I'm over the moon.
"Obviously I hope to follow in some of Mike's (Lord Storey's) footsteps. He's been a councillor for over 38 years and is respected by residents in Liverpool and I wish him well."
Local Lib Dem leader Flo Clucas said the party had suffered at the hands of a national "hate campaign" against Nick Clegg.
"We had an extremely good reception on the doorstep," said Mrs Clucas.
"There was no animosity against those candidates who were standing.
"But as soon as you mentioned the words Lib Dem the words that came back were: 'We all know what Nick Clegg has done. He has jumped into bed with the Tories'."
Mrs Clucas said the national Labour Party had run a negative campaign which she thought was "very bad for politics indeed".
Lib Dem councillor Richard Kemp, who represents Church ward, said his party would come back from the brink.
"I thought we would have done badly, but not this badly," he said. "We have lost some really good people but it's by no means the end of the Lib Dems in Liverpool."
Labour council leader Joe Anderson said: "Liverpool has suffered the worst cuts of any city or town in the country.
"They are hurting but not working. It's no wonder the Lib Dems suffered their biggest defeat in 50 years."
Former Lib Dem leader Warren Bradley had to stand down as the party's leader last month, after an email he had written predicting big losses in the city was leaked.
Labour swept to power in Warrington Council taking six seats from the Lib Dems. The council previously had no single party in control but Labour now has a majority with 34 out of 57 seats.
Labour became the largest party on Sefton council - after it gained five seats and the Lib Dems lost five - although the authority remains in no overall control.
Labour also became the largest single party on the hung Wirral Council with the five seats they took from the Lib Dems, leaving the party with 29 seats to the Tories' 27.
The Lib Dem leader Simon Holbrooke was one of the party's casualties.
Labour retained control of Halton Council, gaining seven seats, and kept hold of Knowsley, where the party took three seats from the Liberal Democrats, two from the Conservatives and two from other representatives.
Labour also strengthened its grip on St Helens where it gained seven seats. The party now holds 35 of the council's 48 seats.
A former leader of Liverpool City Council has lost his seat to an 18-year-old Labour candidate.