The 53-year-old shot a six-under-par 278, one shot ahead of Weiskopf, and then revealed that he had been unsure whether to take part at Sandwich after a nagging shoulder problem had hampered his game.
'I felt if I didn't play well this week I wouldn't play any more this year,' he said.
However, Nicklaus said the shoulder did not bother him at all during the tournament and he now plans to head to Royal St George's.
Nicklaus won around pounds 90,000 for his second US Senior Open victory and at the same time helped erase one of the few bad experiences he has had on this course. In the 1960 US Open at Cherry Hills he missed a golden chance to collect his first US Open title when Arnold Palmer completed one of the game's greatest comebacks to beat him, signalling the beginning of their great rivalry.
Palmer, then 30, recovered from seven strokes behind to pass Nicklaus and win his first and only US Open title.
'I had a flashback at the 12th when I was at five under because I was five under on the same hole in 1960,' Nicklaus said.
'I told my son Jackie I would not play the last six holes the same way I had in 1960 when I went three over par.'