The West Bromwich East MP added that while the party had won over large swathes of voters in inner-city areas, those belonging to the traditional working class needed reassurance to return to the party.
Labour has performed strongly in polls following last month’s general election with a Opinium survey for the Observer putting the party at 45%, compared with 39% for the Tories, while a poll by Survation had the Tories on 41% and Labour at 40%.
The polling figures are significantly higher than the 30.4% of ballots cast for Labour on June 8.
Watson told the Observer: “I think everyone knows now, Jeremy’s position is completely secure as leader.
“He has had a unified [the] PLP [parliamentary Labour party] around him since his second election win, more or less, and now he has got a highly enthused PLP around him, to take him through the years ahead.”
Coral bookmakers are quoting odds of 11/8 that Corbyn leaves his role in 2020 or later - compared with 5/1 that he leaves this year, the Press Association reported.
Watson added that a majority was possible for the party - and that it had to reassure working-class voters on issues such as policing and security.
He told the paper: “If we can bring these young voters, enthuse them to stay with us and then give greater reassurance to our traditional working-class voters, some of whom left us on issues like policing and security, then we’ve got an election-winning alliance, and I think it is an unbeatable one.
“We’ve got a lot of work to do, but I can see a way through.”
He added the party was preparing to have a “busy summer” as it focuses on working marginal seats, after Corbyn visited Amber Rudd’s ultra-marginal constituency of Hastings and Rye on Saturday where the Home Secretary has a majority of just 346 votes.
Meanwhile Watson’s fellow West Midlands MP Jess Phillips has said her decision to vote for Chuka Umunna’s amendment on single market membership should not be considered a rebellion against Corbyn.
She wrote in the Observer: “We live in a time when the way I tie my shoelaces can somehow be misconstrued as an attack on Jeremy Corbyn.
“ Let me be clear, nobody press-ganged me to vote for or against it on either side.
“My constituents voted leave, I respect that, so I voted to trigger article 50, but I’ll be damned if I am going to let Tories decide what a good Brexit looks like for my constituents.”
It comes after Labour chair, and Corbyn ally, Ian Lavery told HuffPost UK no MP has a ‘divine right’ to reselection in future.