The group have signed an online letter calling on the prime minister and home secretary to apologise for their "display of hostility" towards those working in the justice system.
It follows Ms Patel's repeated criticism of lawyers who defend migrants and asylum seekers as "lefties" and "do-gooders".
Mr Johnson also claimed during the Tory conference that the criminal justice system was being "hamstrung by what the home secretary would doubtless – and rightly – call the lefty human rights lawyers, and other do-gooders”.
The list of signatories to the online letter features 14 retired judges, including the former Master of the Rolls, Lord Dyson, as well as 84 QCs and 294 junior barristers, 76 law firm partners and 69 legal professors.
Their statement reads: "We are all deeply concerned at recent attacks, made by the Home Secretary and echoed by the prime minister, on lawyers seeking to hold the government to the law.
"Such attacks endanger not only the personal safety of lawyers and others working for the justice system, as has recently been vividly seen; they undermine the rule of law which ministers and lawyers alike are duty bound to uphold.
"We invite both the Home Secretary and the Prime Minister to behave honourably by apologising for their display of hostility, and to refrain from such attacks in the future."
Earlier this month the president of the Law Society said that the home secretary’s comments had undermined the legal system while the chair of the Bar Council said that Ms Patel was seeking to “demonise” people carrying out a vital public service.
Layers have also claimed that a "violent, racist attack" in which a man entered a law firm in London armed with a knife was inspired by Ms Patel's attitude.
Days after the home secretary complained about "activist lawyers" delaying the removal of failed asylum seekers, a 28 year-old man entered the office of a law firm armed with a knife.
He was subsequently charged with assault, racially aggravated public disorder, possession of, and making threats with, a bladed article in a public place and making threats to kill during the incident on 7 September.