All four men were remanded in custody when they appeared at Bow Street Magistrates Court sitting at the high security Belmarsh court complex in south-east London.
Armed police stood guard outside the court as the alleged would-be suicide bombers arrived for the hearing in police convoys.
Ibrahim Muktar Said, 27, of Stoke Newington, London, was the first to appear. Said, who was charged last night in connection with the failed Hackney bus bombing. is accused of conspiracy to murder; attempted murder; conspiring to endanger life by using explosives and of making or possessing an explosive with the intent to endanger life or cause serious injury on July 21.
Manfo Kwaku Asiedu, 32, of Finsbury Park, north London, was the second suspect to appear in court today. Asiedu is charged with conspiracy to murder and conspiracy to cause explosions likely to endanger life on 21 July. The charges relate to the discovery of a discarded rucksack that was found at Little Wormwood Scrubs, north west London, on 23 July.
The third man to appear in court was Ramzi Mohamed, 23, of North Kensington, London, who is charged with same counts as Said. Mohamed, who allegedly attempted to blow up a bomb on a Tube train near Oval station, was arrested with Said at a flat on the Peabody estate in Dalgarno Gardens, North Kensington, on 29 July.
The fourth man to appear in court was Yassin Omar, 24, of New Southgate, north London. Omar was charged on Saturday in connection with the failed bid to bomb a Tube train at Warren Street. He was arrested in Birmingham on 27 July.
All four men were remanded to November 14 at the Old Bailey.
Three other men were also remanded in custody when they appeared at Belmarsh today.
Siraj Yassin Abdullah Ali, 30, of Curtis House, Ladderwood Way, New Southgate, north London, is charged with failing to disclose information about a terrorist and assisting a person who has committed an arrestable offence.
Wharbi Mohammed, 22, of Tavistock Crescent, Notting Hill, is charged with the same two offences.
Asias Girma, 20, of Corfe House, Dorset Road, Stockwell, south London, is charged with failing to disclose information about a terrorist.
On Saturday, three men were remanded in custody charged under anti-terror laws in connection with the July 21 attacks.
Shadi Abdel Gadir, 22, and Omar Nagmeloin Almagboul, 20, both of Dyke Road, Brighton, and Mohamed Kabashi, 23, of Mary Magdalene Road, Brighton, were accused of failing to disclose information about the failed bombings.
They appeared at Horseferry Road Magistrates' Court, central London.
A total of six people have now been charged under the Terrorism Act with failing to disclose information that could have helped police investigating the 21 July attacks.
The others are Yeshiemebet Girma, 28, who is the wife of Hussain Osman, her sister Mulumebet Girma, 21, and Ismael Abdurahman, 23.
Girma appeared before the court accused of failing to disclose information about Hussain Osman, the suspected Shepherd's Bush bomber who is being held in Rome. Girma was also charged with assisting a person in evading arrest. His legal representative indicated that he would plead not guilty to both offences. He was remanded in custody until August 11 when he will appear before Bow Street Magistrates court, with a committal hearing likely on 1 September.
The failed 21 July attacks took place two weeks to the day after four suicide bombers killed themselves and 52 passengers on the London transport network.
Today's court appearances coincided with a huge security operation at the Belmarsh complex, which is normally home to Woolwich Magistrates Court.
Every car entering the court grounds was searched by a team of police officers while pedestrians were checked in a special security tent.
Armed officers also stood guard at several points and near the entrance to the court, which is next to the high security Belmarsh prison.