The report, however, also warns of the possibility of a global recession next year.
"Weak macroeconomic indices, waning business confidence and rising geopolitical tensions have increased the possibility of a recession in 2020," James McDonald, Managing Editor, WARC Data, said in a statement.
"Within this climate, our forecast of six percent growth in global advertising investment may seem optimistic, but these projections are in line with those from the IMF (International Monetary Fund) and Euromonitor for GDP and consumer spend, respectively," McDonald added.
With global growth of six per cent, 2020 is expected to see a marked uptick from the 2.5 per cent growth in 2019 but is down on the 7.3 per cent rise recorded last year, according to the report titled "WARC's Global Advertising Trends".
Internet formats will account for over half of global ad investment for the first time in 2020, and social media, search and online video - the largest of these - are effectively shorthand for Facebook, Google and (Alphabet-owned) YouTube.
Meanwhile, Amazon is becoming more popular with advertisers, with the e-commerce giant's share of all ad dollars rising to 2.5 per cent. By contrast, Alphabet will grow to 23.1 per cent, and Facebook will grow to 12.9 per cent.
Advertiser investment beyond these three players has been flat or falling since 2012, said the report.
The researchers found that advertisement spend is set to rise across all 19 categories measured for the report.
Eight product categories set to increase advertising investment ahead of the global rate next year are financial services, household & domestic, transport & tourism, telecoms & utilities, technology & electronics, alcoholic drinks, automotive and soft drinks.
Internet is the fastest growing ad medium in each sector except technology and electronics, where out of home (OOH) is set to rise fastest at 11.4 per cent, according to the report.
( With inputs from IANS )