Scalise, 51, and three others were wounded when a man identified as James Hodgkinson, 66, from the St. Louis suburb of Belleville, Illinois opened fire on the Republican lawmakers. More than $1 million has been raised this year for Congressional Sports for Charity.
This year, the charities are the "Boys & Girls Club of Greater Washington, Washington Literacy Center, the Washington Nationals Dream Foundation and, after Wednesday's shooting, the Capitol Police Memorial Fund".
It's a tradition dating back to 1909.
Top US Republican lawmaker Steve Scalise remains hospitalized in critical condition after being shot this week but he has improved, his surgeon said Friday as he expressed optimism about the legislator's prospects for recovery. The game was for healing.
Before they took the field, Democrats and Republicans gathered in prayer around second base as fans chanted "USA, USA".
"We will not be intimidated by threats, acts of violence, or assaults on our Democracy, " President Donald Trump said in a videotaped message at the game. Officer David Bailey recovered enough to throw the first pitch at Thursday's Congressional Baseball Game. "I'm prayerful he will pull through and I hope he does", he said.
Many wanted to show up to the game to support America.
The US president offered the assessment as a shaken US House returned into session a day after the shooting of Mr Scalise and others.
Another attendee, Dana Moore, said, "I'm tried of seeing all the division and everything".
The Democrats won the game, 11-2, behind pitcher Cedric Richmond, a close friend of Scalise's from Louisiana. Scalise's colleagues will take the field wearing Louisiana State University baseball caps as a tribute to his alma mater.
Meanwhile, the Federal Bureau of Investigation is still asking northern Virginians for help in trying to determine a motive behind the attack.
The motive for the shooting remained unclear but authorities were zeroing in on the life of James T. Hodgkinson, a 66-year-old man from IL, in the months and weeks before Wednesday morning's shooting.
Sava added that Scalise "was as critical as you can be when he came in" after a single rifle shot traversed his body from his left hip through internal organs to the other hip as witnesses said he was fielding ground balls.
Dr. Jack Sava, trauma director at MedStar Washington Hospital Center, says several operations have controlled the bleeding and Scalise's vital signs have stabilized. He died after officers in Scalise's security detail and local police fired at him.
Although Scalise was able to talk on the ballfield, by the time he was transported by helicopter to the hospital, he was in shock.