Watford say Andre Gray, Nathaniel Chalobah and Domingos Quina will be available for Saturday’s Premier League match with Chelsea at Stamford Bridge.
The trio were left out of Sunday’s defeat by Southampton after Gray reportedly breached social distancing regulations by hosting a birthday party at his home on Friday.
“We have got to the bottom of it,” assistant boss Craig Shakespeare said.
“They apologised to staff and players both individually and collectively.”
Watford said on Sunday that the decision was made “to ensure the health and safety of all players, staff and officials”.
On Monday, Gray, 29, said he would “do what it takes to make it right”, describing what happened as “a gathering of friends which turned into a sort of football tournament on my birthday”.
Explaining their omission from the 3-1 home defeat against the Saints, Shakespeare added: “That was a club decision. That was the right decision at the time. They have apologised. They’re back in training and fit for selection.
“They’ve admitted they’re wrong. They’ve settled back into it, they know they’ve made a mistake and want to make up for it. The next chance is against Chelsea. If they play their part then all well and good.”
The Hornets are one point above the relegation zone in 17th place with six matches remaining.