Browne, 24, made his debut in a 2-1 friendly win against Latvian side RFS two weeks ago and scored the final goal in a 3-0 Suomen Cup win over TPS Turku a week later, Radio New Zealand International reported.
The Port Moresby-born winger also started in the 2-1 cup win against HIFK on Sunday last week before inking a three-year contract with the club.
"For me Helsinki is a great city and HJK is a great club with so much history and it's great to be part of this club," he told the HJK club website.
"For the season the staff and the management have put together a great squad. The first couple of weeks we've had a good start and for us we want to compete every match and win everything possible."
In a statement announcing the deal, HJK described Browne as: "technically skilled, fast and agile. During less than a month of testing, he proved to be a competitive and ambitious player".
Browne left PNG in 2012 to take up a football scholarship at St Peters College in Auckland. He debuted for nine time OFC Champions League winners Auckland City at the age of 16 and was a part of the team that won a bronze medal at the FIFA Club World Cup in Morocco in 2014.
After spending three years in the youth ranks at Dutch clubs FC Zwolle and FC Groningen he returned to Auckland City for the 2018/19 season before getting his big break with the 29 time Veikkausliiga champions, who finished fifth of 12 teams in the Finnish top flight last season.