The Foreign Secretary said the UK had evidence that development of the nerve agent had continued over the past 10 years - despite Moscow's claims to have destroyed it.
Mr Johnson also revealed that chemical experts will be coming to the UK tomorrow to check the samples from the scene of the attempted murder of former spy Sergei Skripal and his daughter Yulia.
Speaking on the BBC's Andrew Marr show, Mr Johnson said: 'We actually have evidence within the last ten years that Russia has not only been investigating the delivery of nerve agents for the purposes of assassination but has also been creating and stockpiling Novichok.'
The news came as Mr Johnson warned that only Russians would suffer due to Moscow's expulsion of 23 British diplomats and the closure of the British Council.
Mr Johnson said the UK was in the 'Kremlin's crosshairs' because Britain is the country that has 'time and again called Russia out'.
The US, Germany, France and the Baltic countries had all experienced 'Russian meddling, malign, disruptive, Russian behaviour', he said.
'They can see a country that is going in the wrong direction and that's why they are so inclined now not to give Russia the benefit of the doubt and to stand shoulder to shoulder with the UK.'
Mr Johnson said experts from the Organisation for the Prohibition of Chemical Weapons (OPCW) will arrive in the UK tomorrow.
The team from the Hague will meet officials from the Defence Science and Technology Laboratory and police to discuss the process.
Samples will then be despatched to international laboratories selected by the OPCW for testing. Results are expected to take at least two weeks.
Mr Johnson made clear that the government's evidence on Russia suggested it had broken the Chemical Weapons Convention.
Moscow is said to have investigated ways of delivering nerve agents for assassination, and part of the programme involved producing and stockpiling quantities of Novichok.
Branding Vladimir Putin a 'bully', Mr Johnson jibed that his regime was 'isolated'. 'We have friends across the world and he does not,' he said.
Mr Johnson also took aim at Jeremy Corbyn over his unwillingness to condemn Russia over the outrage, saying: 'He let down his party and country by seemingly aiding the efforts of the Russian propaganda machine by casting doubt over what is obvious to any objective onlooker.'
Theresa May has said Britain and its allies are considering their next move and the national security council will meet again this week.
Former double agent Mr Skripal, 66, and his 33-year-old daughter remain in a critical condition in hospital, while Detective Sergeant Nick Bailey, who was exposed to the Novichok nerve agent while responding to the incident, is no longer considered critical.
Russia's Ministry of Foreign Affairs announced yesterday that it had ordered the British diplomats to leave within a week and indicated it could take further action should there be what it called more 'unfriendly' moves.
Writing in the Sun on Sunday, Mr Johnson said: 'These futile measures will only punish ordinary Russians by depriving them of harmless opportunities to learn English and apply for UK visas.
'Today Russia stands alone and isolated.
'That fact demonstrates the most telling difference between Britain and Putin: we have friends across the world and he does not.'
Mr Johnson added: 'We knew there would be risks in opposing the Kremlin - resisting a bully is always risky.
'But we did it anyway because we knew it to be right.'
Speaking at the Conservative Spring Forum yesterday, Mrs May said the Government had 'anticipated' a response to her decision to expel 23 Russian 'spies' from London.
She said: 'Russia's response doesn't change the facts of the matter – the attempted assassination of two people on British soil for which there is no alternative conclusion other than that the Russian state was culpable.
'It is Russia that is in flagrant breach of international law and the Chemical Weapons Convention.'
Mrs May also received support from Labour former PM Tony Blair and her old foe George Osborne.
Asked at the Global Education and Skills Forum (GESF) in Dubai about the British response to the Salisbury nerve agent attack, former prime minister Tony Blair said: 'I think the Government has done the right thing in relation to it.
'It can't allow such a thing to happen and not take action.
'But I think there's a bigger question underlying that, because over the years there's been periodic action taken.
'What this shows is the importance of the alliance and the importance of having the allies in conversation with each other where they are able to work out the strategy for keeping the West strong, because you are defending certain values.'
Appearing on stage at the Global Education and Skills Forum with Mr Blair, Mr Osborne said Russian interference on British soil was 'staggering'.
'No state can tolerate that. No alliance of western states can accept that,' he said.
'People in Britain will know I'm not a completely enthusiastic support of Mrs May, but I think she has done a pretty good job.
'She has ratcheted up the response, she has expelled Russian diplomats and she has got to think... how do I react to the Russian reaction?
'So she has got to keep further options in her locker to make sure that you can increase the pressure.
Meanwhile, counter-terrorism police renewed their appeal for sightings of Mr Skripal's burgundy BMW 320D saloon car, registration HD09 WAO, in Salisbury on the morning of Sunday, March 4.
Metropolitan Police Assistant Commissioner Neil Basu said: 'We are learning more about Sergei and Yulia's movements but we need to be clearer around their exact movements on the morning of the incident.'