Facebook and Google together accounted for over 66 per cent of the global mobile ad spending in 2013, that rose over two-fold to $17.96 billion, compared to 2012.
"Google still owns a plurality of the mobile advertising market worldwide, taking a portion of nearly 50 per cent in 2013, but the rapid growth of Facebook will cause the search giant's share to drop to 46.8 per cent in 2014, eMarketer estimates," it said in the report.
According to Facebook's Q4 2013 results, the mobile ad revenue represented about 53 per cent of advertising revenue, up from around 23 per cent of advertising revenue in the fourth quarter of 2012. Revenue from advertising was $2.34 billion in the fourth quarter of 2013.
"Facebook in particular is gaining significant market share. In 2012, the social network accounted for just 5.4 per cent of the global advertising market. In 2013, that share increased to 17.5 per cent and eMarketer predicts it will rise again this year to 21.7 per cent," the research firm said.
The rapid pace at which mobile has taken over the firm's ad revenue share indicates Facebook's mobile future, it said.
In 2012, only 11 per cent of Facebook's net ad revenues worldwide came from mobile and last year, that figure jumped to 45.1 per cent.
In 2014, eMarketer estimates that mobile will account for 63.4 per cent of Facebook's net digital ad revenues.
Mobile accounted for 23.1 per cent of Google's net ad revenues worldwide in 2013 and eMarketer estimates this share will increase to 33.8 per cent in 2014.
On the global mobile ad market, the research firm said last year, global mobile ad spending increased 105 per cent to $17.96 billion.
"In 2014, mobile is on pace to rise another 75.1 per cent to $31.45 billion, accounting for nearly one-quarter of total digital ad spending worldwide," eMarketer projected.
Combined, the two companies (Facebook and Google) saw net mobile ad revenues increase by $6.92 billion, claiming 75.2 per cent of the additional $9.2 billion that went towards mobile in 2013.
"The two companies are consolidating their places at the top of the market, accounting for more than two-thirds of mobile ad spending last year, a figure that will increase slightly this year," it said.