The comedienne has replaced the late star - who passed away in August on the E! show - and admits it took a number of discussions with Joan's daughter Melissa Rivers before she agreed to be a part of the programme.
She said: "Joan is present on set because Melissa is executive producer.
"So... this decision for me was very much driven by conversations with Melissa and we kind of had honest talks about it that were maybe more from an emotional point of view than to say, 'Do you want the job? This is when it starts. "
Kathy made her debut on the show's 'Golden Globe Awards' special last week and has reassured fans who thought she was "holding back" with her comments that she will now come back "worse".
She told 'Access Hollywood': "The funniest thing is, I think the consensus was that people thought I was holding back a little bit.
"So, look out. I mean, you can't tell me that I was holding back because it just... I fall for it. I'm gonna become worse."
The 53-year-old comedienne-and-actress is excited about casting her eye over the red carpet wear at the forthcoming Academy Awards.
She said: "I'm looking forward to covering it on 'Fashion Police,' because I've been a nominee, I've been a winner, I've been on both sides of the carpet... but that doesn't mean I'm going to hold back on fellow nominees or winners. Everybody's on the market."