The visitors finished the regular season in 11th place, while the hosts secured third spot in the second tier before beating both Partick Thistle and Arbroath in the previous rounds of the playoffs to get to this stage.
Match preview
After four years in the Scottish Championship, Inverness are now just two games away from returning to the top flight and they are in this position courtesy of a dramatic victory in the playoff semi-finals.
Caley Thistle played out two goalless draws against Arbroath and despite finishing the second leg with nine men, following two controversial red cards for Daniel Devine and Wallace Duffy, they managed to win 5-3 on penalties.
Goalkeeper Mark Ridgers made a crucial save to keep out Bobby Linn, before Kirk Broadfoot tucked away his effort from 12 yards to help Billy Dodds's men advance to the final.
Spirits are high within the Inverness camp, as they head into Friday's contest having lost only one of their last 12 league matches. They've also impressed defensively during this run as they have kept seven clean sheets, just two fewer than the number of shutouts recorded in their previous 28 league fixtures.
Inverness suffered a 3-0 defeat the last time they welcomed St Johnstone to the Caledonian Stadium back in April 2017, but they currently boast a four-game winning streak on home soil so they can be confident of success on Friday.
Just under 12 months ago, St Johnstone were celebrating a historic domestic cup double and a fifth-place finish in the Premiership, before experiencing a fleeting spell in the Europa League qualifiers at the start of this season.
Fast-forward to the present day and Callum Davidson's men face the prospect of relegation to the Championship after finishing the regular campaign in 11th place, recording eight wins, 11 draws and 19 defeats.
The Saints head into Friday's fixture off the back of a disappointing 4-0 loss away at Hibernian last weekend, a result which has extended their winless run on the road to eight matches. Indeed, their away form has been a concern for Davidson all season, as they have won only three of their 19 league games away from McDiarmid Park.
Nevertheless, St Johnstone can take confidence from their recent head-to-head record against Inverness, as they have won four of their last five competitive meetings against them, including successive 3-0 wins in their last two encounters.
Seven of the last 10 teams who finished 11th in the Premiership have gone on to win the playoffs and avoid relegation, a statistic which bodes well for the Saints ahead of their two-legged tie.
Inverness Caledonian Thistle Scottish Premiership Playoffs form:
Inverness Caledonian Thistle form (all competitions):
St Johnstone Scottish Premiership form:
Team News
Inverness revealed on Wednesday that they were "astonished" to discover that their appeal against Daniel Devine's red card had been rejected, meaning the defender and Wallace Duffy will miss the first leg through suspension.
The absence of Devine will likely see Cameron Harper brought into the first XI to start at left-back, with Robbie Deas moving over to centre-back alongside Broadfoot.
Midfield duo Roddy MacGregor and Tom Walsh are also set to miss out due to injury, so Sean Welsh and Reece McAlear could retain their places, although Scott Allardice will also be pushing to start.
Top scorer Billy Mckay, who has 15 goals to his name this term, could return to the first XI at the expense of Austin Samuels.
As for St Johnstone, Tony Gallacher (broken foot), Chris Kane, David Wotherspoon (both knee) and Craig Bryson (ankle) are all ruled out through injury.
Callum Hendry will be hoping to return up front, with Nadir Ciftci - who is yet to score for the Saints since joining the club in January - the most likely candidate to drop to the substitutes' bench.
Liam Gordon is expected to replace either John Mahon or Daniel Cleary at centre-back, while Cardiff City loanee Tom Sang could be handed another start at left wing-back ahead of Callum Booth.
Inverness Caledonian Thistle possible starting lineup:
Ridgers; Carson, Broadfoot, Deas, Harper; Welsh, McAlear; Sutherland, Doran, Chalmers; Mckay
St Johnstone possible starting lineup:
Clark; Cleary, Gordon, McCart; Rooney, Butterfield, Gilmour, Sang; Middleton; O'Halloran, Hendry
We say: Inverness Caledonian Thistle 1-1 St Johnstone
A closely-fought contest between two evenly-matched sides is set to be played out at the Caledonian Stadium, although the momentum is with Inverness who will be confident of securing their fifth successive home win when they face a struggling St Johnstone outfit.