NBA pundits believe the 2.03m tall (6'8") Doncic, whose nickname is 'Wonder Boy', could be a perfect fit for the modern NBA, where the ability to create shots and defend multiple positions outweighs towering size and brute strength.
19-year-old Doncic, the EuroLeague MVP who led Real Madrid to the EuroLeague championship this year and Spanish ACB title on Tuesday, is likely to be the heir apparent at the Mavericks to Germany's Dirk Nowitzki, who is 40 years old and expected to retire soon.
"I've been talking to a lot of teams but especially Dallas, who were so nice to me," Doncic said in an interview after he was selected at the Barclays Center in New York.
"I am just happy to be in the NBA," he said with a smile.
Doncic is just the seventh international player to be taken in the top five of the NBA draft, joining the likes of China's Yao Ming (1st in 2002), Spain's Pau Gasol (3rd in 2001) and Latvia's Kristaps Prozingis (4th in 2015).
Doncic already has several years of pro experience, having debuted for Real Madrid in the ACB in 2015 at age 16. He had been on their books since he was 13.
He said his experience in the EuroLeague, which is considered the second best league in the world after the NBA, would serve him well in his rookie season.
"I have a lot of ex-NBA players on my team and I play against a lot of ex-NBA players," he said.
"They have been talking to me about the NBA all year because they knew I was coming so I think I'm prepared."
The Phoenix Suns had earlier selected University of Arizona center Deandre Ayton with the first pick, while the Sacramento Kings had taken Duke point forward Marvin Bagley III with the second.
Michigan State power forward Jaren Jackson Jr. was picked fourth by the Memphis Grizzlies.