The Arsenal forward slotted home the winning spot-kick with an audacious panenka effort to seal Chile’s first ever Copa America crown - much to the jubilation of the home faithful.
With the game locked at 0-0 after 120 minutes, penalties decided the winners, with Ever Banega and Gonzalo Higuain both missing from 12 yards for the Albiceleste.
Sampaoli, who is Argentine but has been in charge of the Chilean national team since 2012, was full of praise for Alexis and the rest of his players.
"Alexis' penalty gave me an unbelievable joy," he said in the press conference, reported by Goal.
"These players did a great job. They went out in search of this Copa. I didn't see one play in the whole competition to suggest that Chile was not better than their rivals.
"I want to enjoy this moment with my players. To have won the Copa America here in Chile, with the people euphoric... I want to say thank you to my players for allowing me to be part of that.”
Sampaoli is being tipped as a potential next coach of his native Argentina, with the passionate trainer sparking elation in Santiago through his direction of the victorious team.
Sanchez will now have a break before returning to North London for pre-season at Arsenal, with the former Barcelona man expected to play a considerable role in the Gunners’ potential title challenge in 2015-16.