The remains, located inside a garbage bag, were discovered by the worker around 9:30 a.m. near South Chickasaw Trail and Suburban Drive, less than four-tenths of a mile from the Anthonys' home on Hopespring Drive.
Orange County sheriff's deputies said it's too early to tell if the body is that of Caylee.
Local 6 News reporter Jessica D'Onofrio confirmed that the remains are likely that of a girl. D'Onofrio said the worker saw the garbage bag, opened it, saw the remains of a child and called 911.
A skull was found nearby, and there was duct tape in and around the garbage bag, D'Onofrio reported.
"Deputies did respond to that area, and once we were on the scene, we determined that we do have the remains of a young child. Obviously, our concern is that it's in close proximity to some recent activity in that part of the county, and it's incumbent upon us to determine what we have," said Orange County sheriff's spokesman Jim Solomons, referring to the Casey Anthony case.
The age and gender of the remains are not known.
The area of the discovery has been blocked off, and FBI agents, along with sheriff's detectives, are investigating the wooded area.
Tim Miller, the leader of EquuSearch, a Texas-based group that has performed numerous searches for Caylee's body, said he talked with FBI agents, who told him that they believe the remains belong to Caylee.
"It would be inappropriate to speculate," Orange County sheriff's Capt. Angelo Nieves said. "Our investigators are on scene, evaluating and processing the situation. It's very early."
Nieves said that George and Cindy Anthony have been notified about the discovery.
Caylee's mother, Casey Anthony, 22, remains jailed in her daughter's disappearance.
Pretrial Hearing
Meanwhile, Local 6 has confirmed that a motion for a change of venue has been prepared by Baez, but the motion has not yet been filed.
A pretrial hearing was held Thursday morning in the first-degree murder case, and Baez waived his client's right to a speedy trial, and the case was moved to the court's March docket. A status hearing was scheduled with a tentative date of Jan. 15. Anthony's trial had been scheduled to begin Jan. 5.
Anthony did not appear at the hearing.
Computer Password Code
Local 6 News continues its investigation into the case as reporter Tony Pipitone deciphers the words and figures Anthony used to communicate with her family from jail.
In a jailhouse visit in July, Lee Anthony, Casey Anthony's brother, seemingly played the role of family detective, but she did not offer much information until he mentioned computer passwords.
"Any meaning behind the passwords that would be clues to any of this?" Lee Anthony asked.
"Yes," Casey Anthony replied.
"Does that include the MySpace sign-in passwords as well as the computer passwords?" Lee Anthony said.
"The computer passwords, no. MySpace and Facebook, yes," Casey Anthony said.
"All right, so there is meaning behind those?" Lee Anthony said.
"Yes," Casey Anthony said.
"Password for that is?" Lee Anthony asked.
"Cays234," Casey Anthony said.
But less than an hour later, Casey Anthony gave her mother, Cindy Anthony, a different answer.
"I don't know your MySpace password," Cindy Anthony said.
"Facebook account (is) timer55 (and the) password is the same as my MySpace," Casey Anthony said.
"I'll let you elaborate if you want to. If not, it's OK," Lee Anthony said.
"Move on to something else. We'll cover that by other means," Casey Anthony said.
The siblings met again in a jailhouse visit three days later, and Casey Anthony communicated with her brother via Baez.
"Do you got anything for me outside of what I've already heard?" Lee Anthony said.
"Did you guys get my messages from Jose?" Casey Anthony asked.
"Yes," Lee Anthony said.
"That's where I'm leaving it , so," Casey Anthony said.
Two days later, on July 30, Cindy Anthony told the FBI that she had figured out her daughter's password code for timer55.
"She told Lee the other day timer55 means that she has 55 days," Cindy Anthony said.
"Fifty-five days from when, as Casey now claimed, mystery baby sitter Zenaida Gonzalez and her sister threw her down in Blanchard Park and took Caylee to teach her a lesson," Pipitone said.
"Fifty-five days to Caylee's birthday, and she said Caylee would be returned on her birthday," Cindy Anthony said.
Caylee's birthday is Aug. 9, which is 55 days after June 16, the day Casey Anthony was last seen with Caylee.
"And that, at least according to Cindy, was the code in Casey's password," Pipitone said.
Mall Video Sought
Baez is seeking a court order for surveillance video of a reported sighting of Caylee.
Baez said that a photograph taken by an unidentified shopper with a cell phone camera, showing a girl who resembles Caylee Anthony playing at a Florida mall five months after she was last seen, led to the request.
The photo was submitted to a tip line in the ongoing search for Caylee.
Baez wants the Florida Mall in Orlando to turn over all of its surveillance tapes from 2 p.m to 5 p.m. on Nov. 16. In a motion filed Monday, he asked a court to subpoena them. No decision has been made yet.
Caylee hasn't been seen since mid-June, but Casey Anthony did not report her daughter missing until mid-July. The child's body hasn't been found.
Baez wants access to the tapes because "in spite of the first-degree murder charges faced by Ms. Anthony, this is still a missing persons case."
"The inability to act could hinder the prompt and safe recovery of Caylee Marie Anthony," Baez wrote.
A call to Florida Mall's director of security was directed to the mall manager, who was not immediately available for comment.
The state's attorney's office did not immediately return a call seeking comment. Prosecutors have routinely declined comment on developments in the case.