The Swede, who is the most decorated male athlete across all sports in Paralympic history, now has 30 medals, including 17 gold, from nine Paralympic Games appearances.
He said: 'If I hadn't won the gold today, I think I would have finished. But now I will take some time off and think about the future.'
He has had a long campaign at London 2012, collecting silver in the men's R1-10m Air Rifle Sstanding - SH1 on Friday.
He failed to make the final in the Mixed R3-10m Air Rifle Prone - SH1 event on Saturday and again missed a medal in the Mixed R6-50m Rifle Prone - SH1 on Tuesday, finishing fourth.
The defending champion in the men's R7-50m Rifle 3 Positions - SH1 was still struggling to find his shape in the qualification round, marking 93 points out of a possible 100 two times in prone position and once in standing position.
Jakobsson qualified second for the final, two points behind Doron Shaziri of Israel but said afterwards: 'I had a psychological advantage when I was up to meet the Israeli athlete because I have beaten him in a couple of similar situations before.'
However, the Swede was sluggish in his first two shots (9.5 and 9.7) in the final. Then he resolutely defended his title by scoring 10s all the way from his third shot to the end of the competition.
Shaziri buckled under the pressure and his performance went downhill. He said: 'It was nerves. It happens. The excitement must have got to me. I managed to relax throughout until the last three shots but overall Jonas Jakobsson shot better than me and mastered the tension.'
With 100.9 points, Jakobsson marked the highest score of the session to clinch the title with a 1,255.9 total. He celebrated the 30th Paralympic medal of his career with a fist pump in response to cheers from Swedes in the crowd.
Shaziri, outclassed by Jakobsson, won silver on 1,252.4 points. The medal is his fourth in this event. He earned silver at Beijing 2008 and Atlanta 1996 and bronze at Athens 2004.
Chinese shooter Dong Chao got bronze with a 1,251.5 total. It is the second medal for him at London 2012 after he won gold in the men's R1-10m Air Rifle Standing - SH1.