Mr Omar, of New Southgate, London, is also charged with attempting to murder passengers on 21 July. He will appear at Bow Street magistrates on Monday.
The 24-year-old was arrested on 27 July in Birmingham and is the first of the four suspected bombers to be charged.
An unnamed man arrested in Finchley, north London, on 2 August in connection with the failed attacks, was released on Saturday.
On or before 21 July 2005, he did conspire with others unknown to cause, by an explosive substance, explosions of a nature likely to endanger life or cause serious injury to property.
BBC News correspondent Jake Lynch said: "Interestingly, of the four charges against him, none of them involve any specific anti-terrorism legislation.
"Despite that, his court appearance, we believe, is going to be in a special court inside Belmarsh prison, in south-east London, which is normal where allegations of terrorism or terrorism-related offences are involved."
Earlier on Saturday, three men were remanded in custody after being charged under anti-terrorism laws in connection with the attempted bombings.
Shadi Sami Abdel Gadir, 22, and Omar Nagmeloin Almagboul, 20, both of Dyke Road, Brighton, and Mohamed Kabashi, 23, of Mary Magdalene Road, Brighton, have been accused of failing to disclose information about the failed bombings.
The men appeared in court in central London.
Six people have now been charged under the Terrorism Act 2000 with failing to disclose information that could have helped police investigating the July 21 attacks.
The others are Yeshiemebet Girma, 28, who is the wife of suspected bomber Osman Hussain, her sister Mulumebet Girma, 21, and Ismael Abdurahman, 23.
The failed 21 July attacks happened two weeks to the day after four suicide bombers killed 52 passengers on the London transport network.