The deal will "open a new chapter" for Iran's economy, President Hassan Rouhani said after the big powers agreed to end the country's enforced isolation and begin to lift sanctions.
Presenting the annual budget to parliament, he promised that 2016 would be a "year of prosperity" for a country suffering from high unemployment and hyperinflation.
Lifting sanctions will allow Iran to resume oil exports to many countries and French oil giant Total, as well as Italy's Eni, are after joint venture contracts in which their Iranian partner would retain majority control.
But Rouhani has tried to end reliance on oil, whose price has plummeted recently partly because of the prospect of Iranian sales taking off again, and, with a 79-million-strong potential market, Iran is definitely open for business.
As the nuclear negotiations neared their close, delegations of ministers and business leaders from France, Germany and Italy travelled to Tehran to make their pitches for markets they have lost to emerging economies such as China and Turkey.
A visit by members of French bosses' union Medef riled Washington in 2014, as the US feared the French would steal a march on them.
With car ownership at only 100 per 1,000 people - six times lower than in Europe - vehicle manufacturers are keen to engage.
France's Renault has already negotiated a minority stake in Iranian carmaker Pars Khodro, according to Iranian officials.
"Iran is a very promising market," Renault chief executive Carlos Ghosn said on the sidelines of the Detroit auto show last week. "Today it's more than one million cars, it has the potential to go to 1.5 or 2 million."
The Iranian transport ministry has said that it wishes to buy 114 airliners from European plane-builder Airbus, which is based in the south-western French city of Toulouse.
Rouhani is due to visit France and Italy at the end of January, raising hopes for Airbus, which has to beat off competition from the US's Boeing.
Iran "is potentially a huge market for Airbus and our competitors", Airbus chief executive Fabrice Bregier recently told the Financial Times, adding the company had already made some contacts.
Opportunities for food and other agricultural exports may be more limited, however, due to the "strong involvement of public firms and semi-public owners of farm land," according to a French agriculture ministry report.
Rouhani said Sunday that sceptics about the nuclear deal's benefits to Iran "were all proved wrong".
"Within a few hours" of the nuclear deal being implemented and sanctions lifted "1,000 lines of credit were opened by various banks," he said at a press conference in Tehran.