Selwood’s year, during which he averaged more than 25 disposals, 4 marks, and 4 tackles per game, was also rewarded with a top five finish in the Carji Greeves Medal (Geelong’s Best and Fairest). He finished the season ranked within the top ten in the league for possessions (613), disposals per game (25.5), and handpasses (327). His total of 63 free kicks earned during the season was also the highest recorded since the AFL began in 1990, breaking the previous record of 54 set by Luke Darcy five years earlier.

Although his age made him ineligible to enter the 2005 AFL Draft, Selwood’s accomplishments during the year led to AFL Talent Manager Kevin Sheehan rating him “the best 17-year-old in Australia”. Bendigo Pioneers regional manager Ray Byrne noted that “ability-wise, Joel was streets ahead of everyone. Even at an early age, he was a standout”. Byrne praised Selwood’s professionalism, writing that he had “never seen a kid prepare in the TAC Cup like Joel [Selwood]. He had a fantastic football brain, he could sort it out within 10 minutes of a game who should be where and (doing) what”. Selwood received an array of accolades and honours as a bottom-aged player, winning mid-year State honours for Victoria Country in the AFL National Championships. His performances in the championships earned him end-of-year All-Australian honours and the Most Valuable Player award for Victoria Country. In addition, he was named in the TAC Cup Team of the Year, awarded a scholarship within the prestigious AIS-AFL Academy, and subsequently captained his older teammates in the annual under-18s International Rules Series in Ireland. His performances in Ireland earned him the Ron Barassi Medal, as the adjudicated Most Valuable Player of the tour. Selwood’s achievements in local football were recognised when he was listed as a finalist in the 2006 Bendigo Sports Star of the Year Award.

Returning in 2006 with the Pioneers, Selwood entered his final year of junior football as one of the top rated prospects in his age group. His achievements at the junior level were recognised early by the AFL Players Association, when he was awarded the Mike Fitzpatrick Scholarship, and the AFL Life Members Education Fund Award. Rewarded with the captaincy of Bendigo for his final season, Selwood again won mid-year State honours for Victoria Country. However, a knee injury occurred only six rounds into the competition forcing him to undergo surgery—his fourth knee operation within two years—prematurely ending his season.

Selwood was drafted by the Geelong Football Club with their first selection, and was the seventh overall draft pick in the 2006 AFL Draft. Although many recruiting scouts viewed him as “the finest pure footballer in the draft”, and a potential top pick, there was still concern surrounding the durability of his knee. Nonetheless, as the equal highest-ever draft pick for the Cats, Selwood made his debut in the opening round of the 2007 AFL Season and missed only four games during the regular season.

Prior to the 2010 AFL season, Selwood was retained as the youngest member of the club’s revamped leadership group. Despite being unable to defend their NAB Cup title over the pre-season, Geelong re-signed Selwood to a new two-year contract with the club. Selwood highlighted his desire to “give a little bit back (to Geelong) by working hard and working through the next era of Geelong football”. During the home and away campaign, Selwood set various personal milestones: in a round six fixture against Richmond, Selwood made a career–high 29 handpasses—also the third–highest recorded in AFL history—while in a round nineteen match against Collingwood he gathered a career–high 20 contested possessions. In total, Selwood made 24 appearances during the season to help the club achieve a 17–5 record and qualify for the finals series in second position on the ladder. Geelong faced a 2009 Grand Final rematch against St Kilda during the first week of the finals series, and were defeated in a qualifying final for the first time in four years. Selwood was restricted to just four disposals in the first half of the qualifying final loss, his lowest return in a half of football since his debut match in 2007. The following week, he responded with a 33 disposal semi-final performance to help Geelong defeat Fremantle and progress to the preliminary final. However, Geelong’s defeat to Collingwood subsequently denied them a chance at a second consecutive Grand Final win.

Selwood and Geelong began the 2013 AFL season on a seven-game winning streak before finishing with an improved 18–4 win-loss record to qualify in second position for the finals series. During the season, Selwood made his 150th appearance for the club and set a club record for the fastest 150 games played from debut (six years and one hundred and four days). In doing so, Selwood surpassed the previous record set by Jack Hawkins (seven years and four days). He also became the third youngest player (25 years, 48 days) in club history to reach 150 games, behind only Ken Newland (24 years, 85 days) and Gary Ablett, Jr. (24 years, 339 days). He also set a VFL/AFL record for the greatest winning percentage amongst 150 game players, having won 124 of his first 150 games (83% winning percentage) since debuting in 2007.

Before the 2009 AFL season, Selwood was appointed to the club’s seven-man leadership group at just 20 years of age. After the 2008 AFL Grand Final loss ended Geelong’s previous season, Selwood and his teammates began their 2009 campaign by capturing the pre-season NAB Cup for the second time in four years. Selwood’s 33 disposals, 11 clearances, and 2 goals earned him the Michael Tuck Medal as the player adjudged best afield in this final. In round five, Selwood made his 50th senior appearance, setting a new VFL/AFL record for the highest percentage of wins inside 50 games. His involvement in 46 victories set a winning percentage of 92 percent. In addition, Selwood’s 50th appearance coincided with the club’s own record-setting effort for the most successful 50 game stretch in VFL/AFL history. Geelong had won 47 out of 50 games—Selwood had been involved in 46—eclipsing Essendon’s return of 46 wins and 4 losses during their dominant stretch during the 1999–2001 seasons.

Selwood’s performances throughout the season firmed his position as Geelong’s top midfielder; he gathered more possessions than any of his teammates and ranked within the top ten throughout the league for clearances per game, contested possessions per game, and inside-50s per game—culminating in his second placing to Tom Hawkins for the Carji Greeves Medal and a nomination to the preliminary All-Australian squad. In 2012, he won the AFLPA Robert Rose Most Courageous Player Award for the second time in his career, sharing the honour with Beau Waters. His impressive first year as club captain was also recognised as he finished runner-up in the AFLPA Best Captain Award voting. Selwood’s accomplishments and achievements at the club were honoured when he was presented with life membership of the Geelong Football Club after just six seasons.

Following his 150th appearance, Selwood displayed an improved goal kicking ability by kicking 17 goals in the remaining 7 games of the season. Coach Chris Scott acknowledged that Selwood had identified goal kicking as an area of improvement within his game, and credited Selwood for taking responsibility to work hard and improve at it. Geelong began their finals series against Fremantle in a Qualifying Final, but were defeated by 15 points. The defeat forced the club into a Semi Final against Port Adelaide—the first finals game between both clubs since the 2007 AFL Grand Final. Selwood contributed 27 disposals, 4 marks, and 4 tackles to lead Geelong to a 16-point victory—his first finals win as captain. The win ensured Geelong’s progression through to the Preliminary Final against Hawthorn, to play-off for a position in the 2013 AFL Grand Final. Despite Selwood’s contribution of 23 disposals, 4 tackles, and 1 goal however, the Cats were defeated by 5 points and finished the season in third place.

Despite his team’s exit from the finals series, Selwood was recognised and rewarded for his individual season through several end of season awards. He was named to his fourth overall All-Australian team as the starting ruck rover, and was honoured with the captaincy for the second successive season. He also won his third consecutive, and fourth overall AFLPA Robert Rose Award as the adjudicated most courageous player. In addition, he placed second for the AFLPA Best Captain Award, eighth overall for the AFLPA Most Valuable Player Award, seventh in voting for the AFL Coaches Association Champion Player of the Year Award, and fourth overall in the Brownlow Medal. Selwood’s 21 votes in the 2014 Brownlow Medal count saw him set a new club record for most career polled Brownlow Medal votes by a Geelong player. With 137 votes across 8 seasons, he ranked ahead of Garry Hocking, who had previously held the club record with 133 votes in 15 seasons. His role throughout the season was demonstrated as he led the team in total disposals (614), tackles (144), clearances (153), and inside 50s (100) while kicking the third most goals (24) and providing the second most goal assists (20). In recognition, he won the club Coach’s Award, as well as his second Carji Greeves Medal as the adjudicated club best and fairest player of the year. He became the seventh player in the club’s history to win at least three Carji Greeves Medal’s.

In the 2015 AFL season, Selwood produced several strong performances early in the season despite the team’s shaky start. Against Gold Coast in Round 3, Selwood led Geelong to a 9-point win with 38 disposals—23 of which were contested possessions—8 clearances, 6 tackles, 5 inside 50s, and a goal. His performance prompted his teammate Mitch Duncan to declare him as “an extraordinary player” whilst his coach Scott suggested that “his teammates should consider it a privilege to be playing alongside him”. In Round 19 against Sydney, Selwood made his 200th appearance for the club and led Geelong to victory with 35 disposals, 6 marks, and 6 inside 50s. His milestone appearance at 27 years of age made him the youngest player in club history to play 200 games. He also became the fourth-fastest player in VFL/AFL history to play 200 games after achieving the milestone in 8 years and 129 days. With the departure of several experienced teammates over the previous three seasons, Selwood was responsible for leading an inexperienced midfield throughout the season. Often matched up against opposition taggers and receiving minimal support, Selwood struggled with consistency. Despite leading the team in several statistical categories and averaging career highs in clearances, Selwood recorded his lowest disposal average since his first year, as well as his lowest disposal efficiency, lowest uncontested possession average, and highest clanger average of his career. His inconsistent performances coincided with Geelong consequently finishing the year in tenth place with an 11–1–10 win-draw-loss record, thus missing out on qualifying for the finals series for the first time in Selwood’s career.

Selwood also failed to be nominated into the All-Australian squad or final team for the first time since his debut season. However, he was once again nominated for the AFLPA Most Valuable Player Award, the AFLPA Best Captain Award, and the AFLPA Robert Rose Award. In March 2018, Selwood played his 250th game, becoming the third-quickest player to reach the milestone in VFL/AFL history.

In May 2020 Selwood was criticised on social media after using his wife Brit, as a mop, after dunking her head in a bucket of water as part of a TikTok video which was later removed from the platform by Selwood. Caroline Wilson later commented on the 11 May edition of Footy Classified that after viewing the video her “pub test went, ‘Nah'” and that “it was pretty stupid” whilst similarly suggesting that the Geelong Football Club were unimpressed with the video.