The retail giant officially opened its store in July, creating 25 full- and part-time jobs after it took over the former Woodwares Mica Hardware Store.
The plans sparked a protest campaign led by traders who felt it would destroy the traditional high street.
However, while some retailers say it has hit their business, many reported customers choosing to stick with their well-known independent retailers.
Billy Hoy is the manager of the well-established Findlay’s Butchers and said that people have remained loyal to some of the independents.
“We haven’t seen any adverse impact on our business,” said Mr Hoy, who has been with Findlay’s for the past 17 years.
“People around here have been loyal to the business. In fact, one or two have said that they have tried Sainsbury’s but decided to come back to us.
“I think they prefer a more specialist service than a supermarket.”
Diana Renshaw, Blue Bean Coffee House owner, was initially lukewarm to Sainsbury’s presence on High Street.
However, Ms Renshaw, who has owned the coffee house for the past four-and-a-half years, said: “It’s very handy for me if I ever run out of supplies; sometimes it is a godsend.
“Everyone has now got used to it. I think initially people were hostile because they didn’t want to see the hardware store close.”
However, it has not pleased some retailers who claim to have lost a large percentage of trade to the supermarket giant.
Zainul Abideen owns convenience store Banana Republic and said that his business has seen a 20 per cent reduction in sales.
He said: “We are a lot quieter now. It always makes a difference when a supermarket comes into a place like this.”
Mohammed Javid, from fellow High Street store Kost Konscious, said: “We have lost a lot of trade; it isn’t just one or two items.”
Portobello Councillor Maureen Child believes local businesses have raised their game in the wake of Sainsbury’s arrival and that initiatives such as the Positive Porty campaign have ensured that independent retailers can continue to thrive there.
“If anything I think that Sainsbury’s arriving has meant that some people have stopped using out-of-town retailers,” said Cllr Child.
A Sainsbury’s spokesman said: “We’re confident our Portobello store has provided increased footfall into the High Street, something that will have benefited local businesses.”