The group, founded in 2016 by former investment banker Jonathan Recanati, will open at 1 Finsbury Avenue Square on 15 September.
The restaurant will offer Farmer J’s all-day grab and go menu, including its customisable Field Trays made with a grain or vegetable base, meat or plant-based main and two sides.
An indoor dining room will feature ‘an abundance of plants and natural materials’, and there will be a large outdoor terrace with umbrellas and heaters.
Farmer J operates three other City sites, in Canada Place, Leadenhall Street and King William Street.
It secured £1.9m investment capital from Imbiba towards its expansion earlier this year.
The group recently pivoted the evening offer at its King William Street site to The Fancy Fork, a concept run by former River Café chef Shuli Wimer.
Farmer J Finsbury will open 7am – 10pm Monday to Frida, and from 10am – 7pm on weekends.