It happened in an office car park near North Service Road and Burloak Drive around 4:50 p.m.
Police say a woman was getting into her 2020 Range Rover when she was approached by a suspect holding a firearm and ordered to get out of the vehicle.
The suspect then fled the scene in a Range Rover, while a second suspect, a woman, left in a Dodge Journey the couple had reached.
Police say the Range Rover was later involved in a collision near Upper Middle Road and Sutton Drive shortly afterwards.
The suspect tried to escape from the scene on foot, but Halton police managed to arrest him, a firearm was eventually confiscated from the Range Rover.
The female suspect, meanwhile, was spotted driving at the Dodge Journey in the Appleby Line and Mainway area moments later, around 5:30 p.m.
He was arrested after traffic was stopped by police.
Joshua Belshaw, 22, of St. Louis. Catharines and Kendra MacLeod, 21, of Welland, face several charges, including gun robbery.
They are being held in custody pending a bail hearing.
The arrests came amid a string of car robberies in the GTA in recent weeks.
Earlier this month, Toronto police charged two suspects with more than 100 offenses in connection with a dozen attempted car robberies over the 11 day east of the city.
Maple Leafs star Mitch Marner also stole his Range Rover at gunpoint outside an Etobicoke movie theater last month, an incident that remains unsolved.
