He urged politicians to defend and preserve the dignity of all Americans, even introducing himself as "a son of this great continent."
The chamber was full of Supreme Court justices, cabinet officials and politicians of both parties, after his speech the crowd stood to deliver a standing ovation.
The Argentine Pope said: "Each son or daughter of a given country has a mission, a personal and social responsibility.
"Your own responsibility as members of Congress is to enable this country, by your legislative activity, to grow as a nation."
"Legislative activity is always based on care for the people.
"To this you have been invited, called and convened by those who elected you."
Pope Francis called for a "delicate balance" in fighting religious extremism to ensure that fundamental freedoms are not trampled on at the same time.
He said: "no religion is immune from forms of individual delusion or ideological extremism," adding that religious, intellectual and individual freedoms must be safeguarded, while combating violence perpetrated in the name of religion.
He spoke strongly about his concern over the deaths of Christians and other religious minorities in the Middle East at the hands of Islamic extremists, warning that the Christian presence in the region is at risk.
The Pope also spoke out on a controverisal topic in the US Presidental race, urging Congress and all Americans to welcome immigrants as fellow human beings and not be afraid of one another.
These words come as deals over Mexican and Latino immigration are being discussed throughout the country.
Francis is the son of immigrations himself after his Italian parents moved to Argentina.
He said that the US was created by immigrants and that many of those listening to him are descended from foreigners, and that this generation must not "turn their back on our neighbours".
"Let us treat others with the same passion and compassion with which we want to be treated," he said.
The Pope also spoke on another issue that creates divisions throughout the US, calling for an end to the death penalty across the world.
He stressed that every life is sacred and a gift and society can only benefit from rehabilitating those convicted of crimes.
