The Afghan leader told participants in an investment conference Afghanistan has made "significant progress in the past 10 years," Khaama Press reported.
"Any country, any company and anyone is welcomed to invest in Afghanistan to help take this country towards more progress," Karzai said.
He hinted Afghanistan will be flexible in negotiating a new security pact with the United States that benefits both parties equally.
"With the Americans we will make a deal in which neither the skewer burns nor the kebab," Karzai said, referring to an Afghan proverb.
The most sensitive issue facing the two nations involves immunity from prosecution for U.S. troops remaining in Afghanistan after NATO forces withdraw.
Washington recalled all troops from Iraq after Baghdad refused to grant U.S. soldiers immunity.