The 38-year-old entertainer joined Ellen, 61, for her third and final episode of Ellen's Greatest Night Of Giveaways on NBC.
Justin issued a public apology last week to his wife of seven years Jessica Biel, 37, for his 'strong lapse in judgement (sic)' while also stating 'nothing happened between me and my costar'.
The Cry Me A River singer had his ebullient personality on display for the giveaway episode filmed before the November 21 incident in New Orleans with Alisha, 30.
Ellen opened the show by sharing a video about the Bender family of Troy, Ohio whose world was turned upside down after patriarch Stan was diagnosed in 2016 with ALS, or amyotrophic lateral sclerosis.
Stan and wife Dee Dee learned of his diagnosis in early December 2016 and didn't tell their three children so they could all relish a last Christmas together without worry.
'It's kind of like we lose a little bit of him each day. His hugs aren't as tight anymore, but he can still hug,' Dee Dee said.
Teaming up: Ellen recruited her friend Justin for the third and final episode of her primetime giveaways
Tight family: Ellen opened the show by sharing a video about the Bender family of Troy, Ohio whose world was turned upside down after patriarch Stan was diagnosed in 2016 with ALS, or amyotrophic lateral sclerosis
Their children Madyson, Tag and Ireland gushed about their father who was given a life expectancy of three to five years.
'It really sucks seeing him like this because he's the strongest person I know,' Tag said with his voice cracking.
Tag said he was particularly proud of his father for controlling his attitude and staying positive amid the medical hardship.
Strongest person: Tag said that his father Stan was the strongest person he knows
Ellen welcomed the family onto the stage and then brought out her friend Justin.
The Grammy-winning singer wore a copper jacket, red trousers, T-shirt and sneakers for his appearance on the giveaway show.
Justin hugged the family members and told Stan that he was 'such an inspiration' while wiping away tears.
Getting emotional: Justin upon meeting Stan told him that he was 'such an inspiration'
'I'm not used to walking onto a show crying,' Justin said.
Ellen asked Justin to retrieve her purse and he opened a gift box for the family holding a debit card.
They then presented the family with a gift of $400,000 from show sponsor Green Dot bank to help with expenses.
Tears flowing: The singer admitted that he wasn't used to coming onto shows crying
Justin talked to Stan as the family hugged Helen and told him how he participated in the Ice Bucket Challenge in 2015 to raise awareness of ALS, also known as Lou Gehrig's disease.
The former NSYNC boy band member after a commercial break asked Ellen to feel his head.
'You're burning up,' Ellen told him.
Getting hot: Ellen touched Justin's forehead at his urging and said he was 'burning up'
'I'm burning up with giveaway fever. And you know, there's only one thing that helps with that. It's not more cowbell. It's if we give stuff away to the whole audience,' Justin said.
Justin then promoted his new sequel movie Trolls World Tour due out next April before he and Ellen gifted the audience with a $500 Fandango gift card for movie watching.
Ellen then asked Justin to turn around as the audience squealed and she lifted up the back of his coat.
Giveaway fever: Justin said he had 'giveaway fever' and danced with a gingerbread man before announcing gifts for the whole audience