The 25-year-old, who will be co-pilot for his father Jacques, will tackle the world's most demanding rally: a 5,000 kilometer (3,000 mile), 10-day marathon, 70 percent of which will be raced over sand.
"Our aim is to finish the race and achieve our goal," a beaming Barron told AFP.
"This race is brilliant for me. It will be easy because we know the route."
Barron, who has been training for a year and a half alongside his father, will ride on one of 500 vehicles taking part in the race.
He will compete in the UTV category for off-road four-wheel drive buggies, a class that was added for the first time in 2017.
Born in Lima, Barron has always been a keen sportsman despite his disability, taking part in swimming, football, cycling, surfing and water-skiing.
He says he's "ready and able to overcome the desert dunes."
A fan of both rock and hip hop music, Barron says he will provide important mechanical assistance to his father.
"I'm going to help him look at the engine, the road and the tyres," said Barron.
He is familiar with the Peruvian terrain that will host the entirety of the Dakar rally this year after Argentina, Chile, Paraguay and Bolivia declined the opportunity due to austerity measures.
In September, he was co-pilot alongside his father in the Desafio Inca race that acted as preparation for the main event and took on the dunes of Ica, in the south of Peru.
The "Barron x 2" team finished seventh.
- No fear -
While Down Syndrome can cause lifelong intellectual disability and development delays, those with the condition can still lead fulfilling lives.
Jacques Barron, a 55-year-old engineer, told AFP that Dakar organizers had no problem with his son taking part.
The requirements were the same as for any other competitor: passing all the medical exams and supplying the necessary documentation.
"Lucas already has the International Automobile Federation licence to participate in the Dakar," Barron told AFP.
He said his son is afraid of nothing and knows what to do if there is a problem.
"He knows how to look at the temperature of the belt, the oil and tyre pressure," said Barron, who has competed in the Dakar five times.
"Lucas's eyes will be the cars' eyes to avoid crashing into another car or any object.
"People with Down Syndrome can develop certain abilities: Lucas can play any sport."
The Dakar will be run from January 6-17, starting in Peru's capital Lima and traversing the southern regions of Ica, Arequipa, Moquegua and down to Tacna on the border with Chile.
The longest, and toughest stage will cover 370 kilometers from Arequipa to Tacna on January 10.
The Barron team's main aim is simply to finish the race.
Lucas Barron has the support of one of his idols, five-time motorbike winner Cyril Despres of France, a friend of his father's.
"Despres wrote to me on Facebook congratulating me," he said, adding that the Frenchman gave him a signed shirt in 2017 -- a treasured possession.