The suspects, aged between 19 and 28, and from Cardiff, London and Stoke-on-Trent, were held a week ago in a series of dawn raids by counter-terrorism officers.
They appeared in the dock at City of Westminster Magistrates' Court in three separate groups.
Each spoke only to confirm his name, date of birth and address, before Senior District Judge Howard Riddle remanded them to the Old Bailey on January 14.
Twelve men were held during the raids by unarmed police on December 20 in London, Cardiff, Stoke-on-Trent and Birmingham.
Two men from Cardiff and one from London have been released without charge.
The nine suspects are charged with conspiring to cause by an explosive substance an explosion or explosions "of a nature likely to endanger life or cause serious injury to property in the UK" between November 6 and December 21, this year.
They are also accused of engaging in conduct in preparation for acts of terrorism between November 6 and December 21, including by downloading, researching, obtaining and discussing materials and methods; researching, discussing and carrying out reconnaissance on and agreeing potential targets; travelling to and attending meetings; and igniting and testing incendiary material.
The suspects from Cardiff are Gurukanth Desai, 28, of Albert Street; Omar Sharif Latif, 26, of Neville Street; and Abdul Malik Miah, 24, of Ninian Park Road.
The suspects from London are Mohammed Moksudur Rahman Chowdhury, 20, of Stanliff House, Tower Hamlets, and Shah Mohammed Lutfar Rahman, 28, of St Bernard's Road, Newham.
The suspects from Stoke-on-Trent are Nazam Hussain, 25, of Grove Street; Usman Khan, 19, of Persia Walk; Mohibur Rahman, 26, of North Road; and Abul Bosher Mohammed Shahjahan, 26, of Burmarsh Walk.
Last week's raids came after several months of surveillance and monitoring by police and MI5.
At the time, the country's top counter-terrorism officer, Metropolitan Police Assistant Commissioner John Yates, said it was "absolutely vital" for the public to remain vigilant.
The operation was the most high-profile anti-terror raid in Britain since April 2009, when 12 men were detained across northern England.