A man in his 20s has been charged with attempted murder after the stabbing of a teenage boy outside a supermarket in Sydney's inner west earlier in the week.

At around 4.30pm on Saturday, police arrested a 29-year-old man and a 23-year-old woman at an address on Foy Street, Balmain, who was later charged with concealing a crime.

Police had appealed to the public for help to find the pair, who are not thought to be known to the victim. An extensive search was also carried out, aided by the dog unit.