Half-year pre-tax profits at WPP, the world's largest advertising group, have risen 36% to £244m.
The figures were boosted by growth in the US and the UK, but the strongest markets are still in Asia, WPP said.
Sir Martin Sorrell, WPP's chief executive, said that "mild expansion" is replacing the "fear phase" that was gripping the market last year.
WPP, whose fortunes are an indicator of companies' optimism about the future, had revenues of £4.4bn, up 3.5%.
WPP, whose clients include Vodafone and Unilever, said sales in the first half to the end of June were boosted by "remarkably strong growth" in the US, the largest advertising market.
In the year to June WPP's like-for-like revenues in the US improved markedly from a drop of 6% in the fourth quarter of 2009 to growth of almost 4% in the first quarter of 2010 and 8% in the second quarter. There was also strong growth in July, the company said.
"In our 25 years of existence, we cannot remember a more speedy recovery or turnaround of a region," Sir Martin said.
Major advertisers, such as consumer goods firms Procter & Gamble and Unilever, have increased their marketing budgets in recent weeks.
And broadcasters and media conglomerates such as News Corp and Time Warner have also reported seeing a recovery in advertising sales.
While advertising continues to grow in the digital market, Sir Martin said that traditional media - television and print - "are showing signs of strength".
WPP's performance was helped by major events, such as the football World Cup, which boosted the firm's African business, where revenues leapt 6% in the second quarter.
In the UK, revenues rose 2.8% for the first six months of the year after improving "substantially" in the second quarter, when turnover was nearly 7%.