In January 2023, Brownlee became a naturalized Filipino citizen, allowing him to play for the Philippines national basketball team.

[4] On November 1, 2013, he was allocated by the Knicks to the Erie Bayhawks team of the NBA Development League, Brownlee averaged 13.85 points, 5.7 rebounds, 2.3 assists, 0.5 blocks and 1.4 steals throughout the regular season.

[5] Brownlee helped Ginebra win the PBA Governors' Cup both in 2016, where he made the title clinching three-pointer at the buzzer in game 6 of the finals,[6][7] and in 2017.

Ginebra coach Tim Cone confirmed the move to replace Charles García with Brownlee after player agent Sheryl Reyes made the announcement on social media.

With the help of Brownlee and Balkman, the Philippine squad was hailed as the 2017–18 ABL season champion by beating Mono Vampire Basketball Club of Thailand in 3 out 5 games in the championship series.

[12][13] After playing in the ASEAN Basketball League, Brownlee returned with the Barangay Ginebra San Miguel who were down 1–3 in the 2018 PBA Commissioner's Cup.

In Game 1 of the 2018 PBA Commissioner's Cup Finals against the San Miguel Beermen, Brownlee led the Ginebra to a 1–0 series lead with 42 points, 7 rebounds, 9 assists and 2 blocks.

He eventually won his first Best Import Award and helped the team capture the Commissioner's Cup title winning the series, 4–2.

[16] He played alongside fellow imports, former NBA player Lamar Odom and Chinese Basketball Association veteran Randolph Morris to reinforce the team.

[17][18][19][20] Before returning to Barangay Ginebra San Miguel for the 2019 PBA Commissioner's Cup, Brownlee signed with Al Riyadi of the Lebanese Basketball League.

[25] In the last game of the 2019 PBA Commissioners' Cup elimination, Justin Brownlee broke again his career-high with 50 points in a 127–123 overtime win over the Columbian Dyip.

[27] In the semifinals round, Brownlee and the Ginebra San Miguel were up against the top-seeded TNT Katropa led by former NBA player Terrence Jones.

[30] On April 22, 2022, he surpassed Billy Ray Bates in the scoring list for imports and at that time, in fifth place with 4,539 points.

On his first game on February 5, 2023, for the 2023 PBA Governors' Cup, he recorded a triple-double of 29 points, 11 rebounds and 10 assists in a win against Rain or Shine.

On March 19, 2023, he recorded a career 502 three-point field goals made and led his team to tenth semi-finals appearance with him on the roster after a win against NLEX Road Warriors.

On March 29, 2023, he helped his team to advance to seventh finals appearance with him on the roster after a three-game series sweep of San Miguel Beermen.

After Brownlee failed a doping test at the 2022 Asian Games, he opted not to play at the 2023–24 PBA Commissioner's Cup pending the extent of the sanction to be imposed on him by FIBA.

[48] He made his debut for the team in the 2023 FIBA Basketball World Cup Asian qualifier game against Lebanon on February 24, 2023.

He led the team in points, rebounds, and assists in the semi-final against Indonesia and the gold medal win over hosts Cambodia.

[57] Brownlee eventually sat out the 2023–24 PBA Commissioner's Cup with his team Ginebra in a bid to minimize the impact of his sanction.