According to Entertainment Tonight, the 32-year-old met with Mason, five, Penelope, three, and ten-month-old Reign at his Malibu, California treatment centre over the weekend.
The outlet claims that the kids' grandmother Kris Jenner brought the children for the visit, rather than their mother Kourtney Kardashian.
A source said: "Scott sees the kids whenever he wants to. Despite all of Scott's addiction problems, he is a great dad and loves those kids with all his heart, and they are obsessed with him."
Kourtney, 36, split from Scott in July after nine years together, with his excessive partying reportedly being the nail in the coffin.
It emerged in October that Scott had quietly checked into a rehab centre shortly before his former brother-in-law Lamar Odom was found unresponsive at a Nevada brothel following an alleged drug overdose.
Scott previously checked into rehab in Costa Rica in March, staying for one week before leaving. He later said he'd only ever intended to stay one week and had always planned to return to treatment in the future.
He also sought treatment in Florida after his split from Kourtney.
Kris, 59, has said publicly that she hopes Scott and Kourtney can resolve their differences, telling Access Hollywood in September: "I don't tell her things like that. Because I don't think that's my place.
"But my kids were brought up to be very forgiving people. My wish is that, you know, they work it out and figure it out and we'll see what happens. He's a great dad and he loves the kids and he loves Kourtney... I love him."
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