The four-time Olympic champion took victory in the 3,000 metres at the Diamond League in Birmingham in seven minutes 38.64 seconds on Sunday.
He will retire from the track at the Diamond League final in Zurich on Thursday to focus on marathon racing.
Farah handed his vest to Andrew Butchart at the end of the race and conceded it will take him two years to get to grips with the marathon so there are no guarantees he will return for GB.
The 34-year-old said: “To be honest, to have achieved what I have achieved has been incredible. If I come out of the marathon and I’m the best at the marathon, I might compete, it depends.
“But as an athlete, the next couple of years, it’s going to take me at least two or three marathons to get it right, to learn from it, it’s not easy. It could be my last time.
“This is it for me, that was my message for Andy - ‘this is me done, take over from me and just inspire them, see what hard work is about and what it takes to be a champion’.
“He has got a great attitude and we need to inspire the next generation. I gave it to him because he’s a great athlete, he gives 110 per cent and is learning over the years. He’s a good guy.”
Farah took the lead with just over a lap left and beat Spain’s Adel Mechaal with Davis Kiplangat third and Butchart finishing fourth.
He will race in the Diamond League in Zurich on Thursday and intends to appear at the Great North Run in September but does not yet know when his first marathon will be.
Farah said: “All I ever wanted to do as an athlete is run for Great Britain. I remember when I did the mini marathon as a kid, I got interviewed and asked what I wanted to do, I said I want to run for Great Britain.
“Now it’s finally done, I won’t be competing for Great Britain, in terms of major championships, I won’t be taking part. It feels a bit sad.
“It has been an amazing week - I’ve managed to have a bit of downtime with the family and relax but emotions have been high coming into this event; not as much as London (for the World Championships) but it is my last time at home and I really enjoyed it.
“I was just thinking about the race and who was there. I had to technically get it right.
“I never dreamed that I would become a four-time Olympic champion and multiple world champion. I now have to see what I will do on the road. I don’t think I’ll have the same pressure so I’ll go and enjoy it.
“Running was a hobby when I was younger but it has become a job and I love it. It can be hard when you get the pressure but the roads will be something completely different.”
Butchart, 25, finished sixth in the 5,000m Olympic final last year - which Farah won - and came eighth in the final at the World Championships earlier this month.
He said: “He (Farah) just said ‘It’s up to you now, do your best, it’s your time to shine.’
“I don’t know (what he’ll do with the vest) but it is such a great gesture for him to give it to me. I’ll definitely look after it and cherish it.
“It’s going to be hard to follow him. We’ll do our best, we always do, but I’m going to miss him massively. He’s a massive inspiration.
“Every year he comes out on top. Every year he is finishing high up in the major championships.”