The currency is up by 1.7% at 19.5495 per dollar as of 7:33 a.m. ET.
"The first US Presidential debate may not sway many voters but has lifted the Mexican peso," Marc Chandler, the global head of currency strategy at Brown Brothers Harriman, wrote.
"The peso, which has fallen by about 1.3% over the past two sessions, has stormed by 1.5% today as the seemingly biggest winner of the debate."
Some currency watchers argued that the peso's strengthening suggests that traders thought Clinton won the debate.
As for the rest of the world, here's the scoreboard as of 7:37 a.m. ET:
- The US dollar index is up 0.1% at 95.40 ahead of S&P Case Shiller home prices, Markit services PMI, and consumer confidence.
- The euro is down 0.2% at 1.1237 against the dollar.
- The Russian ruble is stronger by 0.1% at 63.8488 per dollar.
- The Japanese yen is little changed at 100.38 per dollar.
- The British pound is flat at 1.2967 against the dollar.