Welbeck was available on a free transfer after leaving Watford earlier in October following their relegation from the Premier League last season.
Saturday’s 3-0 defeat at Chelsea was Watford’s third in as many matches, leaving the Hornets one point above the relegation zone with five matches remaining
Premier League: Watford sign former Arsenal, Manchester United striker Danny Welbeck on free transfer
Welbeck, who has won 42 caps for England, has seen his career ravaged by injury, but he is fit again for the start of the new season and has scored 42 goals in 206 Premier League appearances for Arsenal, United and Sunderland
Premier League: Arsenal have 'ammunition' to sign top transfer targets, says head of football Raul Sanllehi
Sanllehi is confident the Arsenal's planning has set them up for a good transfer window even if they lose out on a Champions League spot
Europa League: Arsenal's Danny Welbeck still in hospital after suffering 'significant' ankle injury against Sporting Lisbon
Danny Welbeck was stretchered off during the first half of Thursday's 0-0 draw with what looked like a bad break, his foot twisted backwards after landing awkwardly when going for a header.
Europa League: Arsenal enter Round of 32 after goalless draw with Sporting Lisbon; Chelsea edge past BATE Borisov
Arsenal booked a place in the Europa League knockout stage and extended their unbeaten run to 15 matches despite a 0-0 draw with Sporting Lisbon on Thursday, while Olivier Giroud's first goal of the season sent Chelsea through.
Unai Emery has warned his Arsenal stars to fix their leaky defence in time for Sunday's Premier League clash against Everton.
UEFA Nations League: England defender Kieran Trippier says team must not panic after defeat to Spain
Kieran Trippier says there is no reason for alarm after England slipped to their third consecutive defeat in their Nations League opener against Spain.
The England team began their UEFA Nations League campaign with a defeat at the hands of Spain, with a late equaliser from Danny Welbeck being ruled out by the referee.
Premier League: Pierre-Emerick Aubameyang battling confidence crisis admits Arsenal manager Unai Emery
Aubameyang is yet to get on the scoresheet for Arsenal this term after missing a series of chances in their defeats against Manchester City and Chelsea.
Premier League: Coach Unai Emery wants Danny Welbeck to stay at Arsenal but is ready to offload fringe trio
Unai Emery ruled out the prospect of Danny Welbeck leaving Arsenal but said that Carl Jenkinson, David Ospina and Joel Campbell are surplus to requirements.
Januzaj's superb second-half goal sent Belgium into a last 16 clash with Japan while England will now advance to a second-round meeting with Colombia.
FIFA World Cup 2018: England striker Danny Welbeck says he is mentally stronger after missing out on Euro 2016 due to injury
England striker Danny Welbeck says he has emerged mentally stronger after a knee injury ruled him out of the 2016 European Championships and the 27-year-old is keen to make an impact in next month’s World Cup in Russia.
Europa League: Familiar frailties haunt Arsenal as Atletico Madrid's dogged resistance hands them advantage
Atletico Madrid fought their way back from adversity, exhibited great fortitude and pounced on Arsenal's weakness to take the upper hand in the semi-final tie.
Fantasy Premier League, Gameweek 34 tips: Make Tottenham's Harry Kane triple captain, use wild card or free hits
Gameweek 34 has 14 games, but let’s not get greedy, shall we? Manchester United, Tottenham Hotspur and Chelsea are the usual suspects but with Leicester and Brighton, selection is easier said than done.
Welbeck enjoyed a productive outing in Arsenal’s 3-2 Premier League win over Southampton on Sunday, scoring two goals and earning praise from manager Arsene Wenger for showing signs of his best form following three injury-hit seasons.
Chelsea now trail Tottenham and Liverpool by 10 points with just six games left to salvage a place in the Champions League next season.
Premier League: Danny Welbeck's brace fires Arsenal to victory over relegation-threatened Southampton
Danny Welbeck inspired Arsenal to a sixth straight victory with two goals and an assist in a hot-tempered 3-2 home win over Southampton, to leave the Saints still rooted in the Premier League relegation zone.
Europa League: Arsenal boss Arsene Wenger refuses to condemn Danny Welbeck without seeing replay of apparent dive
Arsene Wenger refused to condemn Danny Welbeck after the striker was accused of diving to win the penalty that inspired Arsenal's 3-1 win over AC Milan in the Europa League on Thursday.
Europa League: Danny Welbeck's double helps Arsenal past AC Milan; Borussia Dortmund, Lyon crash out
Danny Welbeck's controversial penalty and a Gianluigi Donnarumma howler helped Arsenal beat AC Milan in the Europa League 5-1 on aggregate, while Dortmund slumped to a shock exit at the hands of Salzburg.