The 23-year-old is one of three changes to the team which finished the recent game against Australia, with the British Lions lock Andy Reed making a return after a two-year injury absence, while the record cap holder, Scott Hastings, is recalled at centre.
An Army lance corporal, Stewart, who has been chosen primarily for his strength, was initially picked for the Scotland Development XV to play Queensland, but two days later he was promoted to the senior squad. "I was delighted even when I was chosen for the Development side but over the moon when I was called up for the senior squad," he said. "I fully expected to be on the bench. But winning a first cap is great."
Stewart's attributes have been carefully noted by the Scotland selectors. The coach, Richie Dixon, said: "Matt has been under our observation for some time. He is proving to be a solid tight-head and has shown good technique in the line-out."
Bryan Redpath, who took over from the injured Gary Armstrong late in the second half against Australia, retains his place at scrum-half. There is also a positional change with the captain Gregor Townsend winning his 21st cap, albeit at inside centre, the first time he has worn the No 12 jersey. At outside-centre Hastings, dropped for the Australia Test, will win his 63rd cap following an improvement in form.
Doddie Weir has been omitted after a poor display against Australia. Dixon said: "Doddie's work rate against Australia was not as great as it might have been. We talked to him about this and, like the player he is, he has taken our words on board."
SCOTLAND (v Italy, Murrayfield, Saturday): R Shepherd (Melrose); A Stanger (Hawick), S Hastings (Watsonians), G Townsend (Northampton, capt), K Logan (Stirling County); C Chalmers (Melrose), B Redpath (Melrose); D Hilton (Bath), K McKenzie (Stirling County), M Stewart (Northampton), D Cronin (Wasps), A Reed (Wasps), M Wallace (Glasgow High/Kelvinside), E Peters (Bath), I Smith (Gloucester). Replacements: D Stark (Melrose), R Eriksson (London Scottish), D Patterson (Heriot's FP), G Weir (Newcastle), B Stewart (Edinburgh Academicals), G Ellis (Currie).
ITALY (from): Backs: M Cuttitta, D Dominguez, I Francescato, G Guidi, L Manteri, F Mazzariol, N Mazzucato, J Pertile, A Troncon, P Vaccari. Forwards: O Arancio, A Castellani, C Checchinato, W Cristofoletto, G Croci, M Cuttitta, M Giovanelli (capt), A Moscardi, C Orlandi, F Properzi-Curti, A Sgorlon.