The Romanian shooter missed a medal in the same event in 2008 by two millimetres. He blocked that out of his mind in London.
"I just went into it and tried to do my best like I do every time," Moldoveanu said. "I was calm, I did not feel pressure, because I did not know where I was. Now I am overwhelmed. It's crazy."
Mouldoveanu and top-ranked Niccolo Campriani of Italy shot 599 in qualifying to equal the Olympic record by Zhu Qinan in 2004. Zhu, who went on to win the 2004 gold and 2008 silver, qualified 10th, missing the eight-man final by a point.
In the final, Moldoveanu was just a little more consistent, scoring 103.1 to Campriani's 102.5.
Mouldoveanutotalled 702.1 and Campriani 701.5.
Campriani felt the pressure of going into the final as a gold favourite and at had a tough time dealing with distractions.
Campriani slipped off the lead with shots in the 9-ring in the eighth and ninth rounds.
"There was a lot of pressure and of course, I am happy with a silver medal, but I am also happy to get the job done," Campriani said. "It was very hard to deal with, people talking about what I should achieve at Olympics and how many medals I should win as the No. 1 ranked shooter.
"The distraction of high expectations when you still have to shoot a match is not ideal for a sport where Adrenalin is not your friend!"
Gagan Narang of India, who runs a shooting academy in Hyderabad called Gun for Glory, won the bronze with a 701.1 total.
His compatriot, 2008 Beijing champion Abhinav Bindra, finished qualifying in 16th place, two shots out of the final.
Bindra's gold at Beijing was India's first in an individual event. And while Narang did not match Bindra's gold, he was relieved to win the bronze.
"I guess I have a huge (weight) off my shoulders," Narang said. "Bronze is a medal, and this is an Olympic bronze medal, so it's quite exciting."
Cork Niefer of Yorkton, Sask., was 46th out of 47 marksmen in the qualifying round and did not advance.