His mother Maree was a top runner and tennis player, and elder twins Adam and Troy were identified as talented footballers at a young age.

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.

[16] 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.

The Geelong coaching staff had a highlights package made of this performance, to screen to the rest of the team during the match review later that week.

[33] With 18 disposals, five marks, five clearances—the most of any Geelong player—seven inside-50s, four tackles, and an equal game-high four score assists,[34] Selwood helped the Cats to a record-breaking 119-point win, which remains the largest Grand Final margin in VFL/AFL history.

[36] He was also the first to win the AFL Rising Star Award and play in a premiership side within the same season,[18] making him one of the most accomplished first-year players in league history.

[44] His standout season was rewarded when he was selected to play for Victoria in the AFL Hall of Fame Tribute Match all-star game.

[49] 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).

[54] 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.

[58] Selwood helped Geelong compile an 18–4 win–loss record during the season to become the first team in league history to produce three consecutive home-and-away campaigns with 18 or more wins.

[60] During the Grand Final against St Kilda, Selwood addressed the playing group with a "stirring speech"[61] as Geelong entered the half-time break trailing by 6 points.

[11] After averaging 28 disposals and 5 tackles per game over the course of the season, Selwood was also awarded with full All-Australian honours for the first time in his career and had a second successive top-five placing for the Carji Greeves Medal.

[69] For the second successive season, he also led the league for total free kicks earned (59) and finished the year ranked within the top five at Geelong in several major statistical categories.

[73] 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.

[81] His record of 85 wins, together with his numerous awards and achievements, led to Hawthorn captain Luke Hodge proclaiming the milestone as "probably the most highly credentialed 100 games anyone has ever played.

Selwood's performance in the final—during which he gathered a team-high 28 disposals, laid 7 tackles, and kicked 2 goals—were recognised as he placed runner-up in Norm Smith Medal voting for the adjudicated best afield player.

[87] Geelong proceeded to re-sign Selwood on a five-year contract—the first time the club had handed out a long-term contract of that length since Gary Ablett Sr in 1987.

[91][92] 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.

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.

[105][106] Despite a hamstring injury during the 2014 pre-season, Selwood made a recovery to lead Geelong to an unbeaten record over the first five rounds of the 2014 home-and-away period.

[109] In the Qualifying Final against Hawthorn, Selwood gathered 31 disposals, 16 contested possessions, 9 clearances, 6 tackles, and 3 goals but was unable to prevent a 36-point defeat.

[31] 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 and (what ended up being) only time in Selwood's career.

They lost their home Qualifying Final to the eventual premiers Richmond by 51 points, and Selwood struggled in particular with just 19 disposals as he returned from injury.

[144] Geelong entered the 2018 AFL season with Gary Ablett Jr, a two-time Brownlow winner, returning to the club and joining Selwood and Dangerfield in the midfield.

[145] Selwood began the season by playing his 250th game in Round 1 against Melbourne, becoming the third-quickest player to reach the milestone in VFL/AFL history, behind only Wayne Schimmelbusch and Adam Goodes.

Despite this initial success and the promise for the season, Geelong missed out on the double chance for just the third time in Selwood's career as they finished eight on the ladder and barely made the finals.

[131] Despite their minor premiership, Geelong lost their Qualifying Final to Collingwood by 10 points; Selwood was not a key factor, only collecting 18 disposals.

Having ranked highly across numerous major statistical categories from his first year, Selwood is considered one of the most consistent and well-rounded players to have ever played at the highest level.

[183] Because of his aggressive style of play, Selwood has gathered a reputation as a "head-over-the-ball specialist"[184] and for consistently putting himself in positions to break tackles and win free kicks.

[186] Former Brisbane Lions captain Michael Voss agrees, stating: "all he’s doing is keeping his feet, dropping his legs and he’s got a fantastic tenchique [sic] in rolling his shoulder ... Selwood shouldn’t be penalised because he’s stronger than the tackler.