Bus stops, a taxi rank and a drop off point will be created at Newhaven Town Railway Station at a cost of £100,000.
It will make the station more accessible to passengers and contribute towards the regeneration of Newhaven.
The news has been welcomed by Newhaven MP Norman Baker (L.Dem) and leader of Lewes District Council James Page.
Mr Baker said: “In order to meet our commitments to cut carbon emissions we need to encourage a modal shift to public transport and making it convenient is an important means to achieving this.
“The town is going to be the construction base for the Rampion windfarm, we have recently had confirmation that a University Technical College for the town has been given the go ahead and now the station is going to be improved with this interchange. Make no mistake, Newhaven is on the up.”
District council leader cllr Page (East Saltdean and Telscombe Cliffs, Con) added: “We are putting a lot of energy into regenerating Newhaven and are using our planning powers to bring as much investment into the town as we can.
“I welcome the county council’s decision to push ahead with the transport interchange this year as it is an important element of the overall vision to bring new life and prosperity to the town.
“It will help make the town a more attractive place to live, study at the new University Technical College, work or set up business.”
The funding is the result of section 106 money, where developers are obliged to give councils money to offset the impact of developments.
The district council approved planning applications for the Lidl supermarket in 2009 and for an Asda supermarket, petrol station, housing and other businesses on Eastside, Newhaven in December 2012.
Planning permission was granted subject to a Section 106 legal agreement, part of which required the developers to contribute funding towards provision of an improved transport interchange at Newhaven.
In March the county council decided to include Newhaven transport interchange in its capital programme for the next year.
A Southern spokesman said: “We welcome the news that Newhaven Town Station is to get this much needed transport interchange.
“We very much hope that this will encourage more people to travel to and from the station in a more sustainable way.”
County council team manager for infrastructure design and delivery, Mark Valleley, said: “The council is committed to delivering the Newhaven interchange to improve the experience of people who already use public transport and to encourage more people to use it for their everyday journeys.
“However, we need to have further discussions with Newhaven Port and Properties concerning the availability of land in the vicinity of the railway station to try and maximise the benefits of the facilities that will be provided.”