Liam spoke with with producer Ben Winston, who he worked with on One Direction's 2013 This Is Us documentary, on Instagram Live about Bear.
The singer revealed he gets tested for coronavirus before visiting his son.
He told how maintaining contact with his son through the pandemic has been "hard" despite living "up the street" from him.
He said: "I went and saw Bear today we had a little hangout which was nice as I hadn't seen him in a couple of weeks.
"It's hard with the COVID thing as I have to make sure I'm negative before I go over and see him so it's having to wait that couple of days before you can test so...
"He's only up the street and it's dead complicated but he's gotten so big, huge."
Liam moved from his London pad just before Christmas to rent a £5million seven-bed-mansion in Buckinghamshire with his model fiancée Maya Henry.
Liam shared a heartwarming video of Bear just before Christmas, suggesting the youngster could be following in his dad's footsteps.
The pair gave a sweet rendition of Jingle Bells on Jessie Ware's Table Manners podcast.
Cheryl proudly said at the end of the song: "Well done bubba."
As he came in, a clearly besotted Cheryl asked him: "Are you being nosey? What are you doing?"
Jessie and her mum Helena couldn't help but coo over his cuteness.
The 36-year-old podcast star asked: "You're a bit of a cutie aren't you. How are you, bud?"
Cheryl then prompted her son to reply: "Hello".
They then discussed his love for the children's franchise Paw Patrol as he revealed its all he wants for Christmas.
He told the pair how his favourite character is Skye.
The three-year-old also told his mum, Jessie and Helena how he likes "mummy's Christmas tree".
Things turned really adorable when Jessie asked him: "Are you being cheeky?" to which, he replied: "Yeah!"