The Take That singer, who recently confirmed his return to the panel, is said to have agreed a £2 million contract to return for a second year, reports The Sun.
> Gary Barlow 'X Factor' return confirmed: 'I'm thrilled to be back'
Tulisa Contostavlos and Louis Walsh are expected to also sign new deals later this week.
The 'Young' singer - who is currently top of the UK iTunes chart with her debut single - will reportedly see her fee doubled to £500,000.
Simon Cowell has said that Contostavlos's job on the show is safe despite the recent release of a sex tape featuring the star.
> will.i.am: 'Cheryl Cole wasted her talent on X Factor'
Louis Walsh was the first X Factor judge to confirm his return for a ninth series last month.
Kelly Rowland is the only judge not to confirm a return from last year's series, with former judge Dannii Minogue rumoured to be signing a deal to replace her.
Barlow and his wife Dawn are currently expecting their fourth child together.