Juniors

Growing up in the Peace Region of British Columbia meant that Middleton was eligible to curl competitively out of B.C. and Alberta. Middleton curled for the Falher, Alberta based Dustin Turcotte rink for two seasons from 2013 to 2015. After seeing him at the 2013 B.C. High School Championship, Middleton was picked up to also play for the Tyler Tardi rink in 2014.^[3] The team went on to win the BC qualifier for the 2015 Canada Winter Games.^[4] At the 2015 Canada Games, the team picked up a bronze medal.^[1]

Middleton was chosen to be play lead on the Canadian team at the 2016 Winter Youth Olympics, along with skip Mary Fay, Tardi and Karlee Burgess. The team steam-rolled through the opposition, winning all 10 of their games before claiming a gold medal for their country.^[1] In the mixed doubles event, Middleton was teamed up with New Zealand's Holly Thompson. The pair made it to the quarter-finals before losing to the eventual gold medallists of Yako Matsuzawa of Japan and Philipp Hösli of Switzerland.

Middleton fully joined the Tardi junior men's rink in 2016, playing third on the rink. The team won the provincial junior title in 2017. Representing British Columbia at the 2017 Canadian Junior Curling Championships, the team lost one round robin game en route to winning the national championship, defeating Ontario's Matthew Hall rink in the final. The team represented Canada at the 2017 World Junior Curling Championships, where they finished the round robin with a 6–3 record, but lost to Norway in a tiebreaker game. That year, Tardi and Middleton also represented British Columbia at the 2017 Canadian U18 Curling Championships,^[1] losing just one round robin game. However, they were not successful in the playoffs, losing in the semifinal, but rebounded in the bronze medal game, defeating Saskatchewan's Rylan Kleiter.

In 2018, the Tardi rink won another provincial junior title. At the 2018 Canadian Junior Curling Championships, the team would defend their title. After losing three round robin games, the team had to fight through a tiebreaker before winning two playoff games, including defeating Northern Ontario's Tanner Horgan rink in the final. The team represented Canada at the 2018 World Junior Curling Championships, where they were much more successful. The team lost two round robin games, and won both playoff games, including defeating Scotland in the final to claim the gold medal.

In 2019, Team Tardi won yet another provincial junior title. At the 2019 Canadian Junior Curling Championships, the team won their third-straight national championship.^[5] The team lost just one game en route to the title, and defeated Manitoba's J.T. Ryan in the final. The team once again represented Canada at the 2019 World Junior Curling Championships. After posting a 7–2 round robin record, they won both playoff games, including defeating Switzerland's Marco Hösli rink in the final.

The 2019-20 curling season would have been the team's last year of junior eligibility, but they decided to make the jump to men's curling full-time, eschewing the junior ranks.^[6]

Outside of the Tardi rink, Middleton won the CCAA/Curling Canada College Curling Championships in 2018, playing third on the Douglas College curling team.^[1]

Men's

While in juniors, the Tardi rink also played in men's events on the World Curling Tour. The team won their first tour event at the 2016 Prestige Hotels & Resorts Curling Classic. They played in his first Grand Slam event at the 2018 Humpty's Champions Cup by virtue of winning the World Junior championship. They went 1–3 at the event, missing the playoffs. They won another tour event to begin the next season at the 2018 King Cash Spiel. The team qualified for the 2019 Champions Cup by winning the World Juniors again. There, the team went win-less in their four matches.^[7] In their first post-junior season, Team Tardi won the 2019 Prestige Hotels & Resorts Curling Classic, and the next season, they won the 2020 Raymond James Kelowna Double Cash event.

Middleton played in his first BC Men's Curling Championship in 2017 as a member of Team Tardi, going 3-3 at the event. The rink didn't enter playdowns in 2018, but were back at it at the 2019 BC Men's Curling Championship. There, the team were eliminated after posting a 2–3 record. They finally made the playoffs at the 2020 BC Men's Curling Championship, where they lost in the final to Jim Cotter.

Team Tardi did not play in any major events in the 2020–21 curling season due to the COVID-19 pandemic. The next season, they played at the 2021 Canadian Olympic Curling Pre-Trials.^[1] After finishing group play with a 4–2 record, they lost in the B quarter-finals to Glenn Howard. The team played at the 2022 BC Men's Curling Championship, where they were eliminated in the C1 vs. C2 page playoff game against Jim Cotter.

The Tardi rink disbanded in 2022.^[8] It was later announced that Middleton had joined the Jacques Gauthier rink for the 2022-23 curling season.^[2] In their first season together, the team won the 2023 BC Men's Curling Championship and represented British Columbia at the 2023 Tim Hortons Brier.^[9] At the Brier, the team finished with a 3–5 record.