Police Superintendent Jody Weis announced the charges Friday night.
Paris McGee, 20, and Toyious Taylor, 29, are both charged with two counts of murder and one count of armed robbery.
Weis would not comment Friday on who fired the shot that killed the off-duty police officer.
"In cases like this, usually everyone recognizes that it's just so outrageous, it's just so evil that people come forward. There's some cases that will break any code of silence," said Weis. "I think when you just keep going out and talking to enough people, and I think the professionalism of our officers and our detectives and our gang enforcement investigative officers, I think the community wanted to solve the case."
Weis refused to comment on reports that the suspects were engaged in a drinking game in which they dared each other to commit a robbery.
Floyd's mother had reportedly told the Chicago Tribune that the crime was the result of a drinking game involving a dare.
Purple and black bunting is hanging at Chicago Police Department District 7 in Englewood in Wortham's honor. Fellow officers shared their memories of him Friday.
"He was a great man - he was a great officer," said Officer Kevin Spisak. "Truly, he was a great friend, and it's a horrible loss to his family, to his friends, and to us here in the 7th District."
Wortham also was a community leader and a first lieutenant in the Army National Guard. He served two tours of duty in Iraq and had recently returned home to Chicago. He was visiting his parents Wednesdsay night with his new motorcycle.
Police say the four armed suspects pulled up and tried to steal the bike. In an exchange of gunfire, Wortham was hit, and his father, a retired Chicago police office, reportedly shot two of the suspects.
Brian Floyd, 20, died at the scene, and another suspect is being treated for his injuries.
The injured suspect remains in critical condition. Weis said that he will also be charged if he survives.
According to police, the two other suspects fled in a car. They were both in custody Friday. One suspect turned himself in, and the final suspect was caught Thursday night at a traffic stop.
Both of them were questioned Friday, along with the injured suspect.
ABC7 Chicago went to the home of suspect Brian Floyd's family Friday and was told by the person who answered the apartment intercom, "He has no side of the story. He is dead."
Days before his shooting death, Wortham had traveled to Washington, D.C. with Superintendent Weis for the police memorial ceremony there.
Among those whom Wortham came to honor was his friend and fellow officer Alex Valadez, who was killed last year.
"I am truly at a loss for words, and I cannot describe my hurt, my pain, and my anger and anguish over this," said Chicago Police Commander Keith Calloway.
Officers were still recovering from Valadez's death when the news came that Wortham had been killed.
"There's no way on God's green earth I would have thought I would be standing here today in front of you talking about Tom," said Calloway.
The Wortham home in Chatham saw a steady stream of friends come by Friday. Wortham's mother said Friday that she hopes something good will come of her son's death.
Wortham and his family were actively trying to keep peace in the neighborhood. A series of shootings in April prompted more anti-violence efforts in Chatham, which had been seemingly immune to violence.
"So many good people have left their lives or put their lives on the line for the good citizens of Chicago, and we've got to go through it - we don't have the luxury of not doing this, because if we don't win this, then we've all lost it, and I refuse to give up," said Calloway.
Neighbor Debra Banks said the recent crimes in the area were a marked departure from the past.
"It feels as though we've been in a cocoon until now, because our community has been such a lovely blessed community," said neighbor Debra Banks.
6th Ward Alderman Freddrenna Lyle had been working with Wortham to improve safety in the community. Lyle is helping to organize a kind of block party in Cole Park on Sunday, which is across the street from the Wortham family home.
Cole Park has been a trouble spot for violence of late.
"We're still very angry that this young man's life was just snuffed out so senselessly, but what can we do to make this a permanent testament to what he was trying to do - that's what we're gonna work on," said Lyle.
Lyle said the plan was to make a big show of neighbors on the first hot, summer-like day.
Before his death, Officer Wortham had worked to improve safety at the park.
Wortham is the second District 7 officer to die within one year.