The former Blue Peter host, who also presents Countryfile, will step in on the BBC One early evening show for a fortnight from May 17.
His appearance may fuel speculation about being offered a more permanent slot.
Adrian quit the show, and all his other BBC commitments, last month in a move to ITV.
He had been unhappy with moves to bring Radio 2 DJ Chris Evans in to present The One Show each Friday and surprised the BBC by not renewing his contract.
Watchdog presenter Matt Allwright has been drafted in to host the programme this week and next – with comic Paul Merton sitting in tonight (Thursday) and next Thursday when it clashes with Allwright’s main role.
Baker has helped to transform Countryfile into a prime-time hit show after two decades in a Sunday morning slot.