[5] The following year, Anstie was able to finish in the runner-up spot in the same class, with two-second places behind champion Ken Roczen.

[7] This effort was enough for Anstie to be signed by the DNA Shred Stix Star Racing Yamaha team for 2010, where he would make his professional supercross debut.

[8] Competing in the Lites West class, he recorded several top ten finished, including a fourth in San Diego.

[9] Anstie was immediately a factor in the MX2 class, placing in the top ten consistently and finishing third in the first race at the American round.

Anstie would again have a consistent season in the MX2 class of the FIM Motocross World Championship finishing seventh in the final standings, picking up his second overall podium at Lierop in The Netherlands.

Anstie was on the move again in 2014, joining the BikeIT Yamaha Cosworth team, focussing on the MX2 class of the 2014 FIM Motocross World Championship.

[16] For the 2016 FIM Motocross World Championship, Anstie changed teams again, to return to being a factory rider – this time for Husqvarna.

[17] In what turned out to be a dominant season for champion Jeffrey Herlings, Anstie was able to pick up two more grand prix victories and finish in fourth in the final standings.

Despite an injury in the early part of the season, Anstie was able to pick up a further three overall podiums on the way to tenth in the MXGP standings of the 2018 FIM Motocross World Championship.

[24] In the Covid-19 shortened AMA Motocross season, Anstie would finish ninth in the final standings, grabbing a third place in race two at the second round after leading much of it.

A final finishing position of third in the class was accompanied by his first ever AMA Supercross main event win, in the wet at the MetLife Stadium.

Anstie continued to show he was one of the fastest riders in the class throughout the season, culminating in him taking his second professional supercross win at the penultimate round of the year in Philadelphia.

As part of this he rode in the last seven rounds of the 2024 AMA National Motocross Championship for the team, scoring two individual third place race finishes in this time.