Mohammed Vakas was found guilty by an Old Bailey jury of plotting to murder Awais Akram.
Vakas attacked the 25-year-old after discovering he was in a relationship with his sister Sadia Khatoon.
Ms Khatoon, who was married at the time of the attack, had met Mr Akram through social networking site Facebook.
Vakas, his sister and her husband, Shakeel Abassi then plotted the attack on Mr Akram.
Awais Akram suffered third degree burns to 47% of his body
They confronted him near to his flat, stabbed him repeatedly and poured sulphuric acid down his throat and over his head.
The attack left Mr Akram in critical condition, fighting for his life in hospital.
He still faces further plastic surgery operations but will be permanently scarred.
Vakas, 26, of Walthamstow, north east London, was found guilty of conspiring
with Ms Khatoon and her husband to murder Mr Akram.
Judge Brian Barker said: "The facts of this case are horrifying. This was a remorseless and a heartless plan."
This was deemed to bring dishonour to her husband and to both families.Judge Brian Barker
He continued: "It was to punish and kill Mr Akram in the most cruel and sadistic way. The reason can be deduced as being an unacceptable relationship with Sadia Khatoon and Awais Akram.
"This was deemed to bring dishonour to her husband and to both families."
Fellow attackers Mohammed Adeel, 20, also of Walthamstow, and 17-year-old Fabion Kuci, of Harlesden, north west London, were convicted of conspiracy to cause grievous bodily harm.
Police are still seeking Sadia Khatoon, 24, who is believed to have plotted with husband Shakeel Abassi and lured Akram to the scene of the attack.
The pair are believed to have fled to Pakistan just hours after the attack.
Both are still wanted as suspects by the Metropolitan Policein conjunction with Interpol, the Foreign Office and local Pakistani police.
Mohammed Vakas Sentenced To 30 Years In Prison For An Horrific Acid Attack On Awais Akram | UK News | Sky News