The air ambulance pilot took unpaid leave in April following the first phase of his training with East Anglian Air Ambulance.
The Duchess Of Cambridge gave birth to Princess Charlotte on 2 May and since then the family have been spending time at their home, Anmer Hall, on the Sandringham estate in Norfolk.
Open Image Modal
The Georgian country home was given to the couple by the Queen as a wedding present.
William is understood to be in the closing stages of his training to be a pilot with the ambulance team, after which he will transport patients to hospital.
He previously served in the Royal Air Force, most recently as a search and rescue pilot.
Prince William has had several official engagements since the birth of his second child, including awarding actress Sheridan Smith an OBE.
And the Duke, an Aston Villa supporter and president of the FA, watched his club endure a crushing 4-0 defeat at the hands on Arsenal in the Wembley clash on Saturday 30 May.
His return tomorrow marks the end of a break of almost six weeks from his flying duties.
Kate Middleton's Best Pregnancy Looks
(01 of19)
Open Image Modal
At a ceremonial welcome for the president of Singapore at Horse Guards Parade in London in October. (credit:Getty Images)
(02 of19)
Open Image Modal
Attending the Wildlife Photographer of The Year 2014 Awards Ceremony in London in October. (credit:Getty Images)
(03 of19)
Open Image Modal
Visiting the home of Ben Ainslie Racing in Portsmouth Old Town in February. (credit:Getty Images)
(04 of19)
Open Image Modal
Attending the Observance for Commonwealth Day Service At Westminster Abbey in London in March. (credit:Getty Images)
(05 of19)
Open Image Modal
A visit to Resort Studios in Cliftonville in March. (credit:Getty Images)
(06 of19)
Open Image Modal
Visiting the Brookhill Children's Centre in London in March. (credit:Getty Images)
(07 of19)
Open Image Modal
Leaving the Stephen Lawrence Centre in London in March. (credit:Getty Images)
(08 of19)
Open Image Modal
Attending the Action on Addiction Autumn Gala Evening at L'Anima in London in October. (credit:Getty Images)
(09 of19)
Open Image Modal
Visiting the East Anglia Children's Hospice appeal launch event in Norfolk in November. (credit:Getty Images)
(10 of19)
Open Image Modal
Leaving the Christmas Day Service at Sandringham Church in King's Lynn in December. (credit:Getty Images)
(11 of19)
Open Image Modal
On a visit to Barlby Primary School in London in January. (credit:Getty Images)
(12 of19)
Open Image Modal
Arriving on the set of "Downton Abbey" in London in March. (credit:Getty Images)
(13 of19)
Open Image Modal
Arriving at the the Royal Variety Performance at the London Palladium Theatre in November. (credit:Getty Images)
(14 of19)
Open Image Modal
Leaving the Northside Center for Child Development in New York City in December. (credit:Getty Images)
(15 of19)
Open Image Modal
Visiting the Emma Bridgewater Factory in Stoke on Trent in February. (credit:Getty Images)
(16 of19)
Open Image Modal
Attending the St Patrick's Day Parade at Mons Barracks in March. (credit:Getty Images)
(17 of19)
Open Image Modal
Attending the St. Andrews 600th Anniversary Dinner at the Metropolitan Museum of Art in New York in December. (credit:Getty Images)
(18 of19)
Open Image Modal
Arriving to attend a coffee morning at Family Friends, a voluntary organisation providing mentoring services to families in deprived areas, in London in January. (credit:Getty Images)
(19 of19)
Open Image Modal
Leaving St. Paul's Cathedral after a Service of Commemoration for troops who were stationed in Afghanistan in London in March. (credit:Getty Images)