His first-team debut for Arsenal came on 25 October 2005 in a League Cup match against Sunderland at the Stadium of Light, as a late substitute for Quincy Owusu-Abeyie.

[17] Bendtner's first Premier League goal came on 22 December 2007 in a 2–1 Arsenal victory in the North London derby against Tottenham Hotspur at the Emirates Stadium.

He headed the winning goal from a Cesc Fàbregas corner just 1.8 seconds (official time) after coming on as a substitute for Eboué, breaking the previous record.

[35] On 5 May 2009, the 21-year-old Bendtner was seen leaving a nightclub hours after Arsenal's 3–1 home defeat by rival side Manchester United in the Champions League semi-final, pictured with his belt undone and jeans pulled down.

[43] He started his first match after recovering from his injury and played 82 minutes in Arsenal's victory over Liverpool on 10 February to complete his return to full fitness.

[47] Four days later, he scored a stoppage-time winning goal against Hull City to put the Gunners level on points with Chelsea at the top of the Premier League.

[51] After worsening his groin problem during the 2010 World Cup, and spending almost four months out of action,[52] Bendtner's first appearance of the season came as a substitute against Birmingham City on 16 October.

[61] On the last day of the August 2011 transfer window, Premier League club Sunderland completed a one-year loan deal for Bendtner; the striker linked up again with manager Steve Bruce.

[65] His first goal came on 1 October to begin Sunderland's comeback from 2–0 down to draw with West Bromwich Albion, and he made the cross from which Ahmed Elmohamady equalised.

[74] On the last day of the August 2012 transfer window, Bendtner joined Italian Serie A club Juventus on loan for the season, with an option to make the move permanent.

[85] On 1 January 2014, Bendtner scored his last goal for Arsenal against Cardiff City in the 88th minute, injuring his ankle in the process before Theo Walcott sealed a 2–0 win.

Managing director Klaus Allofs described him as "a striker at the best age, who already was able to gather a lot of international experience in his career, which did not always run in a straight line".

[77] On 19 March 2015, he scored an 89th-minute winner against Inter Milan at the San Siro to secure a 5–2 aggregate victory that took Wolfsburg to the quarter-final of the Europa League.

[94] Bendtner began his second season at Wolfsburg with the 2015 DFL-Supercup against Bayern Munich: he produced a "poacher's finish" in the 89th minute from Kevin De Bruyne's cross to draw the game level at 1–1 and then scored the winner in the penalty shootout to clinch the trophy.

[95] On 8 August 2015, he continued his good form by scoring in a 4–1 win at Stuttgarter Kickers in the first round of the 2015–16 DFB-Pokal, and opened his Bundesliga account for the season two weeks later with a goal in a 1–1 draw with 1.

[120] He was the youngest player selected for Denmark's squad for the 2006 European Under-21 Championships,[121] and replaced Morten "Duncan" Rasmussen in the Danish starting line-up.

[132] Bendtner turned down the opportunity of representing his country at the 2011 European Under-21 Championships because he wanted to "spend some quality time with [his] young son".

[135] In friendlies in November, Bendtner scored against both Sweden and Finland; in the latter match, he "finished a fine counterattacking move to net the winning goal".

A Sports Illustrated preview described him as "tall and powerful, capable of acting as a target man, yet also has the technical gifts to play deeper or on the flank.

After scoring his second goal, Bendtner revealed the logo of bookmakers Paddy Power on the waistband of his underwear, in an instance of ambush marketing for which UEFA banned him for one 2014 World Cup qualifying match and fined him €100,000.

[138][139] On 12 October 2012, he scored the equalising goal in a 1–1 draw with Bulgaria in a World Cup qualifier, and received a yellow card when playing against Italy four days later.

[140] An ankle injury sustained on club duty with Arsenal resulted in Bendtner being sidelined from international football until a friendly against England at Wembley Stadium in March 2014, in which he played the first 63 minutes.

[141] In the first round of international call-ups after Bendtner's transfer to Wolfsburg, he was left out of the Denmark squad by Morten Olsen, who named Martin Braithwaite as his sole striker for a friendly against Turkey and a Euro 2016 qualifier against Armenia.

[143] He was named in Denmark's preliminary 35-man squad for the 2018 FIFA World Cup, and retained his place when the group was reduced to 27, but a groin injury sustained on club duty meant he was not included in the final 23.

"[147] Despite his talent and confidence in his abilities, Bendtner often struggled with injuries, which limited his fitness; he was also criticised in the media for his perceived arrogance, mentality, and inconsistency, as well as his off-field antics, and as a result, he has been accused of failing to live up to his potential.

[5][82][147][148] In November 2009, it was reported that Bendtner was seen in Hyde Park with former Baroness Caroline Iuel-Brockdorff, a socialite and close friend of the Danish royal family.

In March 2015, Danish celebrity tabloid Se og Hør bought him a square foot of land in Scotland to bestow him the title of "Lord", and according to his agent, he considered it a "fun gimmick".

[153] Bendtner has also taken part in the joke, uploading on Instagram a poster of him holding the Ballon d'Or and running as a candidate for Prime Minister in the June 2015 Danish election.

[156] During the COVID-19 pandemic, Bendtner began playing Counter-Strike: Global Offensive, and became the owner of a small CSGO team called Prosapia Esport.

In November 2022, he participated in a showmatch at the BLAST Premier Fall Finals at the Royal Arena in Copenhagen, playing on Team Denmark.