Welcome to Yorkshire and A.S.O had been trying to extend the race after its success over the last three years.
Cycling’s world governing body the UCI has now confirmed the decision, with the four-day race being included on their 2018 Europe Tour calendar between May 3 and 6.
The Asda Women’s Tour de Yorkshire will also double in size next year, increasing from one to two days.
The extension means that there will be eight start and finish destinations for the 2018 race, and these are set to be announced on Thursday, September 28. The full route will then be unveiled on December 5.
Welcome to Yorkshire Chief Executive Sir Gary Verity said: “This is absolutely tremendous news and something we have long been working to achieve. We are grateful to British Cycling for supporting our application, and to the UCI for granting us this extension.
“Seeing the Tour de Yorkshire grow into what it is today is one of my team’s very proudest achievements and none of this would have been possible if the people of Yorkshire - and Great Britain - hadn’t taken the race to their hearts.
“This decision will help us attract even bigger names in the future and allow us to design a more varied and spectacular route."
Tour de France Director Christian Prudhomme added: “The size and passion of the crowds has not just impressed me, but the cyclists too. They are always blown away by the reception they receive and are already looking forward to coming back in 2018.
“Extending the race to four days will allow us to visit more parts of the county and put on an even greater show.”
British Cycling Chief Executive Julie Harrington said: "We welcome the decision by the UCI to endorse the increase in duration of both the men's and women's races at the Tour de Yorkshire as a sign of the fantastic work done by Welcome to Yorkshire in collaboration with British Cycling in building an event which inspires people across Britain to get active by getting on their bikes.
“We look forward to working with the Tour de Yorkshire team to finalise arrangements."