The former EastEnders star made her name co-hosting the Channel 4 morning show with Vaughan in 1997, but left in 1998 when she found out he had negotiated a larger pay deal than her.
Van Outen told the Mirror: "Johnny and I have had a bit of a rocky relationship over the years for various reasons and, funnily enough, we’ve messaged a lot in lockdown."
“These situations make you reflect and realise some of the silly niggles and arguments you have are just not worth it.”
And their renewed friendship has come just in time as The Big Breakfast, whose hosts also include Chris Evans, Gaby Roslin, Zoe Ball, Richard Bacon and Kelly Brook, is set to celebrate its 30th anniversary.
Van Outen said: “It would be nice to do something.”
The 46-year-old singer, actor and TV presenter left The Big Breakfast in 1998 amid rumours of a feud with Vaughan, 54.
She returned to co-host the show in 2000 and was also reunited with Vaughan in 2008 when they co-hosted a show on Capital FM, but Van Outen left the show halfway through her contract.
She previously said of their working relationship: "We were proper mates. I laughed every day, we used to laugh to the point where I was going to wet myself. Then things happened and we've had fallouts along the way.
"There's are couple of reasons why ... when the show [The Big Breakfast] became successful and we were negotiating contracts I thought we were doing it as a team but his agent had other ideas and she got him more money, and there were all those arguments that happens with bands and presenters. I wanted us to be a team and it became apparent we were not a team anymore and we never got back on track."
The Big Breakfast ran on Channel 4 between 1992 and 2002.
Read more: Johnny Vaughan welcomes new baby
During its Takeover Day schedule, Channel 4's flagship shows will be hosted by all-Black talent, including Celebrity Gogglebox, Countdown and the Channel 4 News.
There will also be a special hour-long episode of soap Hollyoaks which will be entirely written, directed and performed by its Black talent.
Watch: Denise Van Outen talk about getting engaged to Eddie Bosxhall