The charge came as police apologized to Tia Sharp's mother after they failed to find the girl's body in her grandmother's house the first three times they searched it.
Scotland Yard blamed "human error" and apologized for "the distress and concern" caused by the delay in finding Sharp's body, which was discovered Friday in the house—her last known whereabouts—one week after she disappeared in south London.
Stuart Hazell, the 37-year-old partner of Tia's grandmother Christine Sharp, has been charged with murder and will appear in court on Monday.
Two others, a 46-year-old woman arrested on suspicion of murder and a 39-year-old man suspected of "assisting an offender," have been bailed to return to a London police station, they said.
Neither suspect was identified by name in line with British practice, and police did not disclose what relationship, if any, the suspects had with the victim. The Press Association and the BBC said the woman was Christina Sharp, and the man was a neighbor.
It is not yet known how the schoolgirl died, and a post-mortem examination is expected to take place Sunday.
The discovery of Tia Sharp's body led to anger and disbelief in Britain.
The Daily Mirror newspaper asked its readers "WHY DID IT TAKE COPS 8 DAYS?" with the figure 8 outlined in red. The Daily Mail was even more critical, writing under a bold-faced "SHAMBLES" headline: "Despite a week-long hunt by 100 police with dogs, Tia is found dead in her granny's house, which officers had searched THREE times."
Police have not specified exactly where in the house the body was found, but Scotland Yard Commander Neil Basu said Friday they had been juggling several different leads with detectives sifting through 60 sightings of the missing girl, 300 calls, and 800 hours of surveillance footage.
Associated Press writer Cassandra Vinograd contributed to this report.