In 1995, Alker turned professional. He has competed on several
tours around the world. He has been a member of the
PGA Tour of Australasia since 1995. He played on the
European Tour in 1998 and 1999, also competing on Europe's developmental
Challenge Tour in 1999. In 2000, he won the
Canadian Tour Order of Merit. Shortly thereafter, Alker moved to the
United States. He competed on the
Buy.com Tour, the
PGA Tour's developmental tour, in 2002. He was successful enough to graduate to the full
PGA Tour in 2003 but was unable to retain his card and returned to the development tour from 2004 to 2006. In 2007 and 2008, he went back to Europe to play on the European and Challenge tours. He returned to the PGA Tour's developmental tour in 2009. At the 2014
Cleveland Open on the Web.com Tour, Alker beat
Dawie van der Walt on the 11th playoff hole, a tour record for longest playoff. He finished 20th in the
Web.com Tour Finals to earn his PGA Tour card for the 2014–15 season. In 2016, Alker played in
The Open Championship after tying for second place in the Final Qualifying event held at the
Royal Cinque Ports Golf Club.
Senior career In November 2021, Alker won the
TimberTech Championship on the
PGA Tour Champions in
Boca Raton, Florida. With the win, Alker had earned $896,207 in nine senior tournaments after turning 50 years of age in July 2021. This amount was more than he made in his PGA Tour career. Alker continued this form into the
2022 season, recording wins at the
Rapiscan Systems Classic and the
Insperity Invitational. He also finished runner-up at the
Mitsubishi Electric Championship at Hualalai and the
ClubCorp Classic; losing in a playoff on both occasions. In May 2022, Alker won his first senior major championship at the
2022 KitchenAid Senior PGA Championship at
The Golf Club at Harbor Shores in
Benton Harbor, Michigan. Alker shot a final round 63 to win the championship by three strokes. This was his third win in five starts and fourth in 19 as a senior. In November 2022, Alker finished third at the
Charles Schwab Cup Championship which secured him first place in the season-long
Charles Schwab Cup and the $1,000,000 first prize. He also won the Arnold Palmer Award for the season-long money title and the
Byron Nelson Award for the lowest scoring average for the 2022 season. In November 2023, Alker won the
Charles Schwab Cup Championship at Phoenix Country Club, defeating
Ernie Els and
Stephen Ames by a single stroke. This victory secured second place for Alker in the season-long
Charles Schwab Cup and a $500,000 annuity. In March 2025, Alker won the
Cologuard Classic. ==Professional wins (23)==