Organic growth in the year was 20 per cent, according to the group, which operates in Spain and Portugal plus Latin America and Miami.
Llorente & Cuenca issued a press release on its full-year results today (15 February) but did not provide details on profits.
The company said it had doubled income in just over five years. Latin America, where it operates 11 offices in nine countries, now accounts for 65 per cent of income.
The agency grew its headcount by 131 to 482 in 2015; 46 of the new staff arriving as a result of organic growth, and 85 due to acquisitions.
French private equity firm MBO Partenaires acquired a 22 per cent stake in the agency last summer as it targeted expansion. Since then, Llorente & Cuenca has acquired stakes in four companies: Cink and Impossible Tellers in Spain; Brazilian company S/A Comunicação; and EDF Communications in the US.
José Antonio Llorente, founding partner and chairman of Llorente & Cuenca, said: "2015 was an extraordinary year for the company, crowning a decade of sustained growth in which we managed to double our income. This achievement is particularly significant if we bear in mind the complex backdrop against which we have carried out our activities.
"Furthermore, it has been a decisive year in which we have accomplished important acquisitions that have strengthened our position as the leading communications consulting firm in Spain, Portugal and Latin America."