"The Nobel Committee made the right decision in welcoming his tireless efforts to bring a just and lasting peace to Colombia," Obama said yesterday.
"This award is a testament to President Santos's unwavering, courageous leadership through years of difficult negotiations."
The Nobel committee raised eyebrows by giving Obama the prize in 2009, just months after he entered the White House.
It surprised again on yesterday, giving the award to Santos just days after Colombian voters rejected a peace deal between the government and the Revolutionary Armed Forces of Colombia (FARC).
"But it's also a sign that the national dialogue Colombia needs is taking place now and is building on the momentum created by four years of difficult negotiations.
"President Santos and the citizens of Colombia are reshaping their country for the better, and I am pleased the Nobel Committee is recognizing their work as they keep pushing toward peace.