The 49-year-old steps up from his role as under-21s boss and will very quickly have a chance to qualify the Green and White Army for Euro 2020.
Here the PA news agency takes a look at the key things in Baraclough's Windsor Park inbox.
Euro 2020 qualifying
O'Neill had intended to take charge of the play-offs as his final act as Northern Ireland manager, but the delay caused by the coronavirus pandemic made that impractical alongside his duties with Stoke. Instead, the opportunity falls to Baraclough and what an opportunity it is – taking over a team two games away from reaching a second major tournament in the space of four years. But capitalising on it will not be easy. On October 8 they travel away to Bosnia and Herzegovina, a side who beat them home and away in the Nations League in 2018, and would then face either the Republic of Ireland or Slovakia at Windsor Park should they make it through that fixture.
That game against Bosnia in Zenica will be Baraclough's third game in charge, with Nations League games against Romania and Norway first up in September. O'Neill used the inaugural edition of the tournament to overhaul Northern Ireland's playing style, focusing more on retaining possession and introducing pace into the side, rather than relying on set-pieces. The rewards would be felt in the Euro 2020 qualifying campaign, but only after O'Neill's side lost all four Nations League games. They were spared relegation to League C by a reshuffle of the competition, but there must be a greater focus on the league this time around to prevent Northern Ireland slipping too far down the rankings.
Finding a goalscorer
Kyle Lafferty may be Northern Ireland's second highest goalscorer in history, but his last strike for his country came in November 2016 and his club career appears uncertain, released this summer by Sunderland after starting the season with Sarpsborg in Norway. Finding someone who could finish off the chances Northern Ireland's new style of play created proved a major challenge for O'Neill, and it is one that will now fall to Baraclough to solve. The 21-year-old Shayne Lavery, familiar with Baraclough from the under-21s, has shown potential but looks very raw, and more immediate answers are needed.
The next generation
O'Neill did much to rebuild the Northern Ireland squad following Euro 2016 as stalwarts including Chris Brunt, Gareth McAuley and Aaron Hughes moved on and young players including Jamal Lewis, Bailey Peacock-Farrell and George Saville established themselves. But there is much work to do with captain Steven Davis now 35 and limited depth behind the Premier League pairing of Jonny Evans and Craig Cathcart at centre half. The Irish FA clearly hope their under-21s manager knows who the stars of the future are.