Charlie Rowley, 45, and his partner Dawn Sturgess, 44, collapsed on 30 June after coming into contact with a small bottle containing the nerve agent.
The couple were contaminated in the town of Amesbury, near the city of Salisbury where Russian ex-spy Sergei Skripal and his daughter Yulia were poisoned with novichok in March.
Mr Rowley and the Skripals survived, but Ms Sturgess died on 8 July and the mother-of-three’s death is being treated as murder.
Lorna Wilkinson, from Salisbury NHS Foundation Trust, confirmed Mr Rowley had left hospital, saying: “Charlie has been through an appalling experience most of us could never imagine.
“Today is a very welcome milestone in his recovery and all of us here at Salisbury Hospital wish him well as he continues to get better.”
Public Health England said Mr Rowley’s release does not create a risk to the public.
PHE medical director Paul Cosford reiterated its previous advice: “Do not pick up any items such as syringes, needles, cosmetics or similar objects made of materials such as metal, plastic or glass. If you didn’t drop it, then don’t pick it up.”
Last Friday, the Metropolitan Police confirmed they had found a small bottle they believed was the source of the contamination.
Mr Rowley told relatives he remembers giving Ms Sturgess what appeared to be a small perfume bottle before the pair were exposed to the nerve agent, which was developed in the Soviet Union during the Cold War.
Detectives are looking at the possibility that Ms Sturgess tested the spray on her face and hands, believing it to be perfume.
A post-mortem got under way this week to try to establish the precise cause of her death.
The results may help inform the process to establish conclusively whether the novichok was from the same batch that was used in Salisbury to poison the Skripals.
Police believe they have identified the suspected perpetrators of the novichok attack on the Skripals, it was reported this week.
Britain has blamed Russia for the novichok poisonings of the Skripals and the accidental poisoning of Mr Rowley and Ms Sturgess – with Russia denying the charges.