Vaughan has not played a competitive match this year since undergoing surgery on his right knee last December.
But after a fitness test at Edgbaston on Sunday under England's supervision, he was added to the squad to face Scotland at Headingley in the C and G Trophy.
"I couldn't have asked for a better start," Vaughan said of his first competitive cricket of 2006.
His innings - containing nine fours and a pulled six into the West Stand - followed five months spent on the sidelines, save for one non first-class appearance for England in February, recovering from surgery on his right knee.
England will be without him for the final Test against Sri Lanka in Nottingham this week - and even after that Vaughan is not about to predict a likely date for his return to international cricket.
"I must stress that this is the beginning - I won't be playing for England on Friday," he said.
"I need to get through a few games to test it out thoroughly over a two or three-week period.
"I'll try to play all the games I can for Yorkshire and see how it reacts to some four-day cricket."
Vaughan has been careful throughout not to rush back, having had to fly home from England's tour of India three months ago when he suffered a recurrence of discomfort in his knee.
Another setback stopped him playing for Yorkshire at Northampton earlier this month - making the 31-year-old doubly determined to be as sure as he could be about his fitness this time.
"I felt good. In my own mind I've been confident over the last two weeks," he said. "I haven't said anything because I didn't want to then have another setback. I kept very quiet and told all the team who were helping me to keep quiet.
"I wouldn't have played today if I didn't think I could do a good job for Yorkshire. You have to give this game a lot of respect."
Vaughan showed no signs of being restricted in any of his stroke play - and appeared to be right at the top of his form as Yorkshire cantered to a Duckworth-Lewis victory.
"I've felt in tremendous form with my batting, doing a lot in the nets.
"You know it's only nets and you have to produce it in the middle. But I felt as good as I have done for a long time in the middle today."
The next stage of Vaughan's comeback is planned to be in Yorkshire's Liverpool Victoria County Championship match at home to Hampshire this week - when he can expect to come up against his old Ashes rival Shane Warne.