Jett was born eight weeks early by emergency caesarean and weighs 5lb 2oz. He is said to be "doing well" in hospital.
Katie's son was born earlier this week and he made his appearance after the former glamour model was dramatically rushed into hospital with complications while on holiday in a European country.
During what was already a tough pregnancy, Katie - who is married to stripper and builder Kieran Hayler - was told her amniotic sac had torn.
The star had no choice but to stay in hospital in the unnamed country after driving there for a road trip holiday with Kieran.
In February, Katie revealed she and Kieran were expecting their first baby together.
During her pregnancy, Katie openly spoke about suffering from bad morning sickness and how she had got a low iron count, which left her feeling exhausted.
Appearing on ITV1's Daybreak, Katie said: "It's the worst pregnancy. I've had lots of problems with being anaemic, low platelets, [I'm] a lot heavier than I was before."
Earlier this summer, Katie was due to fly to Australia to launch her debut shoe line. However, doctors told her she could not fly so the trip has been postponed until later this year.
It is for this reason that Katie - who is also mum to Harvey, Junior and Princess - booked a driving holiday on the continent with Kieran and the kids.
However Katie's brother Daniel flew out after she was admitted to hospital and brought Junior and Princess home so they could go on holiday with their dad, Peter Andre, to Australia.
Katie and Kieran married in the Bahamas on 16 January after a Christmas engagement just weeks before.
See more celebrities who have given birth in 2013 in our gallery below:
Copyright: Love & Lust London