But, she added, her National Front (FN) party needed to undergo a "profound transformation" in order to create a "new political force."
Estimates based on partial results showed Macron winning 65-66.1 per cent of the vote compared with 35-33.9 per cent for Le Pen.
Le Pen said she had called Macron to wish him success.
"I called Mr Macron to congratulate him on his election, and because I have the country's higher interest at heart I wished him success faced with the huge challenges France is facing," she told supporters at a post-election FN gathering in Vincennes near Paris.
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Le Pen said the contest against the pro-EU Macron had confirmed a new faultline "between patriots and globalists".
But the FN would have to "profoundly renew itself to be equal to this historic opportunity and the expectations expressed by the French in this second round," she warned.
"I suggest we begin a profound transformation of our movement to create a new political force," she said, adding: "I call on all patriots to join us.