Umair Hussain, 24, was one of 25 people arrested since police staged pre-dawn raids on August 10 in connection with the plot. Five have since been released without charge.
Police were granted warrants by a court to quiz the remaining eight until next Wednesday.
Under British anti-terror laws, suspects can be detained for up to 28 days without being charged, subject to regular court approval.
Hussain was charged under anti-terror legislation for failing to disclose information about his brother, Nabeel Hussain, who is believed to be one of the eight still in custody.
Umair Hussain will appear at City of Westminster Magistrates Court on Friday.
"Officers from the Metropolitan Police Anti-Terrorist Branch have this evening charged a man under the Terrorism Act 2000 following the anti-terrorist operation overnight on 9/10 August 2006," a police spokesman said.
Hussain "had information which he knew or believed might be of material assistance in preventing the commission of another person, namely Nabeel Hussain, of an act of terrorism and failed to disclose it as soon as reasonably practicable," he said.
Charity link
Of the 11 others facing charges, eight are facing the most serious charges of conspiracy to murder and preparing acts of terrorism, and were told to return to court on September 4 to appear before the Old Bailey criminal court in central London.
The three others are to return to the magistrates' court on Tuesday. Of the three, two were charged with withholding information about an impending terrorist attack.
The third, a 17-year-old youth who cannot be named because he is a minor, was accused of possessing a book about bomb-making, suicide notes and wills, and a map of Afghanistan with information "likely to be useful" to someone planning an attack.
Meanwhile, Britain's charity watchdog said it had frozen the bank accounts of the aid group Crescent Relief, which raised funds for earthquake relief in Pakistan, as part of a probe into whether money was diverted to the alleged terror plot.
"The inquiry will focus on whether or not the charity's funds, or funds raised on its behalf, were used unlawfully. It will also consider the financial policies and practices of the charity," the commission said in a statement.
The Times newspaper said that Crescent Relief, which mobilized for the October 8 earthquake in Pakistan, was founded in 2000 by Abdul Rauf, the father of Rashid Rauf, who is being held in Pakistan over the plot.
Rashid Rauf is one of two Britons being held along with five others in Pakistan in connection with the terror plot.