Work started today (Monday) on the £450,000 cycle lane along Old Shoreham Road from Hove Rec to BHASVIC.
Signs are warning road users and pedestrians to expect six months of delays as work takes place between The Drive and Dyke Road.
The council is contributing about £125,000.
The scheme was approved by Councillor Ian Davey, the council’s cabinet member for transport and the public realm, in August.
Announcing the scheme the Green Party councillor said: “This shows the council meeting manifesto commitments to improve cycling facilities.
“Where we build cycle lanes we want them to be excellent, user-friendly and safe lanes which link to existing routes and facilities and really improve everyone’s experience of moving around the city by bike.
“This is a crucial east-west route across the city but traffic speed and volume can make it an uncomfortable place for cyclists and pedestrians.
“The proposed scheme will make Old Shoreham Road safer for everyone including young people using the many nearby schools.”
Most of the work should be finished by Easter next April.