Footage from Sky Sports appeared to show the ex-Wales boss taking first-team training less than 24 hours after the Black Cats hit a new low in a 2-2 draw with Millwall.
The result made Sunderland the first team in English football history to go 20 home games without a win - and made an appointment to replace the sacked Simon Grayson a matter of urgency.
Press Association Sport understands Coleman has agreed a two-and-a-half-year deal with the Black Cats, and he is expected to be officially unveiled early this week.
The 47-year-old's decision to move to the north-east has come as some surprise given the reputation he built in guiding Wales to last year's European Championship semi-finals.
He will take over a club whose stay-away owner Ellis Short has admitted he will listen to offers, and which is in serious danger of dropping into League One next season.
Coleman's predecessor Grayson lasted just 18 games - of which he won only one - and bemoaned the fact he had not been given enough time in an interview on BBC Radio 5 Live's Sportsweek programme on Sunday.
Grayson said: "I suffered the consequences of not winning enough matches and not being given enough time to turn it around
"I had no disbelief with the group of the players that I had that we wouldn't be able to turn it around, and I'm sure Chris will be thinking the same thing.
"I think the biggest thing Chris will need is time because it does not happen overnight
You can't turn a club around so quickly when it's been through some real dark stages, and that's what he will need to make it a success again."
Grayson revealed he only met Black Cats owner Short twice - once during his appointment process, then after the first game of the season in the Championship.
"I met (Short) when I was interviewed for the job and at the first game of the season and that was the last I heard or saw of him," added Grayson.
Source : PA