She won a Danny Kyle Award with her old band Malinky in 1999 and has been an ever-present performer – in various guises – at the festival since then.
But her fondness for the Glasgow winter event goes back even further than her early singing performances.
"I was going to Glasgow University in 1994 and remember getting a compilation CD that had been released to promote the festival, and hearing so much great stuff," recalls the singer.
"I bought a whole load of tickets I couldn't really afford! Then I remember going in for the Open Stage with Malinky and winning the award, so Celtic Connections launched my career.
"The first time I got booked at a festival was there, as an unaccompanied singer, and that was a launch pad – a year later I had quit my job and had become a full-time musician.
"That would never have happened without Celtic Connections."
This year Karine has two separate shows lined up.
Tonight she is appearing in Red Clydeside at St Andrew's In The Square, the show that is paying tribute to the late singer and campaigner Alistair Hulett, before she headlines her own gig on February 2 at the City Halls.
While Karine's own writing is not as fiery as some of the other acts appearing at the Red Clydeside gig, she does have a way of putting her points across in a subtle manner.
A forthcoming project will see her look at environmental politics, and the 42-year-old feels she can put her points across without being forceful.
"I don't know if I would say I was mellow, you should ask my husband that," she says with a chuckle.
"I am kind of thoughtful, though. I like to think about things and understand them. Before being a musician I was a philosophy tutor so I am interested in asking questions about the way things are.
"I am not a strident person, although once I form an opinion I am very happy to talk about it. Anyone who comes to a show will get a sense of the person I am from the way I talk about what the songs mean, but I am not writing songs for a picket line or a march, they are not those kind of songs."
Her songs have become acclaimed, however, and last year's Traces record was her most successful album yet.
"I wanted to do something that was a little bit different, and produce something that was coherent," she says.
"The way I have approached albums before is looking at the individual songs and going from there, rather than thinking about how the songs would fit together. This time I wanted them to hang together well. I do not want to just do the same stuff every time."
For her City Halls gig she will be joined by American singer Anais Mitchell and her collaborator Jefferson Hamer, who release their eagerly awaited album Child Ballads later this year.
Yet Karine is not concerned about being upstaged by the duo – she requested them.
She adds: "I am just looking forward to performing with Anais. She is right up there as one of my favourite singers and I can't wait to hear her play songs from her new record."
"I asked for that bill when I was asked what I was interested in because it would mean I would get to see her gig! I am also going to play with a five-piece band.
"There is always a risk that the person who is opening up for you is going to be better. But we are totally different kinds of things, I admire her stuff and how she does it."
Karine is an admirer of many things, including – according to a recent comment on her Twitter page – Adele's James Bond theme Skyfall.
"I tip my hat to people involved in hits like that because it takes skill to have something that appeals to so many people and sells so many copies," she says.
"If anyone fancies commissioning me to write a song for a film I will give it my best shot although I am maybe more art house documentary than Hollywood smash.
"Then again, a friend of mine from Manchester is having one of her songs in a Danny Boyle film, so you can never tell what will happen.
"If you write about things that matter to you, the best thing you can hope for is that they matter to someone else. If that someone is a Hollywood film director, then hallelujah."
n Karine Polwart appears at Red Clydeside, tonight, St Andrew's In The Square, £14, 7.30pm and then on February 2, City Halls, £15, 7.30pm.