They are expected to share the costs of commissioning and producing large-scale shows in the next few years under a new partnership forged by their artistic directors.
It is expected to help both events - which have a combined ticket-buying audience of more than a quarter of a million - cope with the impact of freezes in their public funding.
The move, which could see at least one joint production staged each year at both events, has emerged after Celtic Connections confirmed it would be reviving two hit shows from this year’s EIF in its 18-day 2017 programme.
Singer-songwriter Karine Polwart’s stage show Wind of Resistance, which had a sell-out run at the Royal Lyceum in the summer, will be back at the Tron Theatre in Glasgow.
The Mitchell Theatre will play host to Flit, accordionist Martin Green’s show which saw Portishead’s Adrian Utley, Mogwai’s Dominic Aitchison, and singers Becky Unthank and Adam Holmes perform at the EICC.
One of the hot tickets at this year’s EIF - a live version of the ground-breaking musician Martyn Bennett’s final album - was originally commissioned by Celtic Connections in 2014. From Scotland With Love, King Creosote’s acclaimed show which married new music and song with archive film footage, was staged at the EIF months after a sell-out Celtic Connections gig.
Donald Shaw, artistic director of Celtic Connections, revealed he unsuccessfully tried to persuade Sir Jonathan Mills, the predcessor of current EIF chief Fergus Linehan, to embrace Scottish music.
He said: “I used to write every year to complain. It felt strange that the biggest arts festival in the world was in Scotland and yet it had no representation of Scottish music whatsoever, but nothing happened. We’re really happy about creating a relationship with the EIF.
“With Fergus looking at having a more contemporary music strand, it allows us to have a conversation about what would work for both festivals.
We’re not competing in terms of the time of the year or geographically. It just seems to make a lot of sense.
"We don’t have much lee-way in terms of a commissioning budget for creating shows. It would be about whether the idea fitted for both of us, but it would be nice to do one or two a year that had real resonance.”