Junior Bradshaw, 30, and Kevin Liverpool, 33, both from the Manchester area of northwest England, were taken into custody Monday morning after residents reported a suspicious-looking vehicle near Stone's home in Cullompton, about 175 miles southwest of London.
According to several UK media outlets, authorities found swords, rope and a body bag in the car, as well as maps and aerial photos of her secluded property. However, police have not confirmed.
The men were charged Wednesday with conspiracy to commit robbery and conspiracy to commit grievous bodily harm.
Stone's publicists would not say if the 24-year-old singer was home at the time of the arrests, but said she was being kept up to date by the police.
"I'd like to thank everyone for their concern but I'm absolutely fine and getting on with life as normal while the police continue with their enquiries," Stone said in a statement.
Meanwhile, two police officers remain stationed outside the gates to Stone's house, which is on a quiet country road.
Stone won a Grammy Award in 2007 in the R&B category for her collaboration with John Legend and Van Hunt on a cover of Sly and the Family Stone's "Family Affair," and is a member of rock supergroup Super Heavy with Rolling Stone Mick Jagger, reggae scion Damian Marley and Dave Stewart of Eurythmics. She has also taken acting roles, including that of Henry VIII's fourth wife, Anne of Cleves, in TV drama "The Tudors."
Stone is due to start a European tour in July.
The Associated Press contributed to this report.