Signed out of high school by the Seattle Mariners, he spent the next several years pitching for their minor league teams.

[1] His father is Australian celebrity trainer Rob Rowland-Smith, known as "The Sandhill Warrior," and his mother Julie is a retired high school physical education teacher.

[1] The Seattle Mariners, one of the only Major League Baseball (MLB) teams that scouted Australia at the time, signed Rowland-Smith as a non-drafted free agent on 19 November 2000.

With Wisconsin to begin the season, he appeared in 12 games (eight starts), posting a 1–2 record and a 6.75 earned run average (ERA).

[7] He appeared in 18 games (six starts) with Everett, posting a 4–1 record, a 2.77 ERA, 58 strikeouts, and 58 hits allowed in 61+2⁄3 innings pitched.

[1] He spent the season with the Double-A San Antonio Missions, setting a career high with 122 innings pitched.

He made 25 relief appearances for the team, posting a 3–4 record, a 3.67 ERA, 50 strikeouts, and 35 hits allowed in 41+2⁄3 innings before getting promoted to the Mariners in June.

[11] Griffey wound up being the first batter Rowland-Smith faced; he struck him out, proceeding to pitch 11⁄3 scoreless innings in a 16–1 Mariners loss.

[18] He collected his first save April 8 against the Tampa Bay Rays in Seattle's 6–5 win, tossing 1+2⁄3 innings and retiring all five batters he faced while protecting one-run lead.

[22] He faced Oakland again in his final start of the year on 27 September, allowing three runs in 6+2⁄3 innings this time but picking up the win in a 7–3 victory.

[6] [26] He lasted seven innings in his first start back on 24 July, allowing four runs and taking the loss in a 9–0 defeat to the Cleveland Indians.

[27] Five days later, he limited the Toronto Blue Jays to two runs over seven innings and picked up his first win of the year in the Mariners' 3–2 victory.

[28] Three times in 2009, he threw a season-high eight innings, including a game on 16 September when he limited the Chicago White Sox to one run in a 4–1 victory.

[29][30] Rowland-Smith made his last start of the year for the Mariners on 3 October, holding the Texas Rangers to one run over 6+2⁄3 innings in a 2–1 victory.

2 starter.In fact, Rowland-Smith started the 2010 season as the third starter in the Mariners' rotation, behind Felix Hernandez and Ian Snell.

After the game, he was placed on the disabled list with a lower back strain, which Rob Neyer of ESPN speculated was a "phantom injury" designed to get him off the roster, since the Mariners could not send him to the minor leagues without exposing him to waivers.

[39] Upon his activation from the disabled list, Rowland-Smith was mainly used out of the bullpen except for the last game of the season, 3 October, in which he gave up two runs in five innings and had a no-decision in a 4–3 loss to the Athletics.

[1] However, Rowland-Smith was the Mariners' nominee for the Roberto Clemente Award, given annually to the MLB player who "best represents the game through extraordinary character, community involvement, philanthropy and positive contributions, both on and off the field.

"[41][42] Seattle made him their candidate because of his work in hosting the Mariners Care Cystic Fibrosis Foundation golf tournament.

[41] In November 2010, the Sydney Blue Sox named Rowland-Smith as one of the players on their 35-man roster for the inaugural Australian Baseball League season, but he never pitched for them.

[47] He was excited about joining Arizona because they were opening their season with two regular-season games in March against the Los Angeles Dodgers at the Sydney Cricket Ground in Australia.

[1][49] He made what would be his last appearance in the major leagues on 14 April, giving up two runs (one earned) in the final two innings of a 7–3 loss to the New York Mets.

[52] He pitched for the Triple-A Buffalo Bisons of the International League, allowing 8 runs in just 14 innings before drawing his release on 11 June.

He made one start for the Louisville Bats of the International League but was mostly used out of the bullpen, posting a 4.20 ERA in 12 games with no wins or losses.

[1] For 2015, Rowland-Smith left the United States, signing with the EDA Rhinos of the Chinese Professional Baseball League, located in Taiwan.

He played for Australia in the 2004 Summer Olympic games, making four relief appearances, going 2–0 with a 1.23 ERA allowing only six hits and five walks while striking out 5.

In Australia's second game of the qualifier (the first against South Africa), Rowland-Smith pitched three scoreless innings in relief of Warwick Saupold, allowing two hits and striking out three.

[65] It was Australia's fourth-straight World Baseball Classic qualified for, but they failed to advance past the first round, going 1–2 with a win over China and losses to Japan and Cuba.

[66] Rowland-Smith became a baseball television analyst for Root Sports Northwest, appearing on the pre- and post-game shows for Seattle Mariners broadcasts starting in 2017.

[72] In June 2019, Rowland-Smith appeared on the television show American Ninja Warrior in the Seattle Qualifying Round.