Transport Minister Meegan Fitzharris, who will take over responsibility for light rail from July, owns an investment property on Northbourne Avenue.
Ms Fitzharris's husband Pierre Huetter bought the apartment at 79 Northbourne Avenue in Turner in 2001. Now a rental property, it remains in Mr Huetter's name and is in the section of Northbourne that will benefit from Ms Fitzharris' announcement of $2 million in upgrade works to verges and footpaths.
The works announced on Thursday were approved in 2014, before Ms Fitzharris was elected to the Assembly.
The apartment, ageing former student accommodation opposite Havelock House, could also increase in value from the tram development. The government's business case points to increases in property prices and rents of between 5 and 20 per cent in other cities with light rail developments.
Apartments in the complex sold for about $128,000 in 2002 and have had few sales in recent years. One apartment sold for $303,000 in 2013.
Mr Huetter is a prominent figure in the Labor Party's right faction.
The apartment and the family's Gungahlin home were declared on Ms Fitzharris' register of interests when she entered the Assembly in March 2015.
Appointed Transport and Municipal Services Minister in January, she will take over responsibility for the tram project from Capital Metro Minister Simon Corbell from July.
Ms Fitzharris, a former chief of staff to Chief Minister Andrew Barr, said she did not consider the apartment presented a conflict of interest.
Under provisions of the government's ministerial code of conduct, she advised Mr Barr that her statement of interests was correct before her appointment in January.
"This is public information and has been since I declared it in my register of interests when I first become an MLA," she said on Friday.
"The funding for the upgrades to the Northbourne Avenue footpath was announced in May 2014, before I was a minister, or even a member of the Legislative Assembly.
"The upgrades will make the path much safer for the thousands of pedestrians and cyclists who use Northbourne Avenue each day."
Opposition transport spokesman Alistair Coe said the government should have disclosed the investment property before Thursday's announcement of footpath widening and verge improvements.
Mr Coe linked the issue to the controversy this week over an agreement between the government and trade unions on procurement contracts.
"The revelation that a $2 million footpath upgrade appears to be on the doorstep of a minister's family investment property should have been declared to the media outlets reporting on the funding," he said.
"In light of this week's integrity issues for the government, ministers should be on high alert to make sure that they're doing everything possible to remove any perceptions of conflicts of interest."
Mr Barr defended the $2 million in verge and footpath upgrades on Friday and said the government continues a regular program of maintenance on footpaths around Canberra, worth about $3 million each year.
The first stage of upgrades on Northbourne Avenue will include footpath widening and verge upgrades between Greenway Street and Barry Drive and Cooyong Street.
The existing 1.2-metre-wide path will be replaced with a new 2.5-metre surface. Bollards will be removed from verges as part of a 12-month trial and some trees would be trimmed and street lights reorganised.
Construction is scheduled to begin in June or July, and take about three months, ahead of major construction for the tram later in the year.