Mickelson won the event at Castle Stuart last year before going on to triumph in the Open at Muirfield seven days later and McIlroy believes the 2014 event at Royal Aberdeen is perfect preparation for the following week's Major at Hoylake.
McIlroy, whose previous Scottish Open experiences came at Loch Lomond, said: "I can think of no better preparation for the Open, especially on a respected course like Royal Aberdeen. There will also be so many similarities I can bring to the following week's Open Championship.
"Phil winning the double last year made me realise that the Scottish Open is more than good preparation for the Open - he showed it was possible to win both weeks.
"You can play as much golf on links courses as you want, but until that's in a competitive environment you can never tell how ready your game will be. It really is so important, then, to get some competitive golf on a true, challenging links."
Mickelson has already confirmed his participation in the July 10-13 event.