Initially playing for their reserve team, Paulsen signed his first professional deal in September 2021 and largely served as second-choice goalkeeper.

On 14 November 2020, Paulsen finally made his reserves debut, starting in a 1–0 loss to Team Wellington in the opening game of the 2020–21 season.

[19][20] In June 2024, Paulsen signed for Premier League club AFC Bournemouth for a reported initial fee of £850,000, rising up to £2 million[2] on a 4 year contract.

Paulsen made one appearance, as a late substitute in a 6–1 win over Samoa, as New Zealand won the title and qualified for the 2020 Summer Olympics.

[25] In September 2022, Paulsen was first called up to the senior national team for a two-game friendly series against Australia, but did not play in either match.

[26] He was later called up for friendlies against Greece and Ireland in November 2023, and then in March 2024 for two FIFA Series matches against Egypt and Tunisia, but again did not play ahead of incumbent Max Crocombe.

[27] On 18 June 2024, Paulsen finally made his senior international debut, keeping a clean sheet against the Solomon Islands in a 3−0 2024 OFC Men's Nations Cup win.

[31] The brothers played futsal regularly growing up, and Paulsen attributes this as a major influence on his ball-playing ability as a goalkeeper.