His declaration comes despite earlier comments about Mexicans seen as deeply offensive by many.
Mr Trump has accused Mexico of sending "criminals" and "rapists" into the US.
He has also made building a border wall with Mexico a key tenet of his campaign and repeatedly said Mexico is "killing the US" on trade deals.
Extending an apparent olive branch, the billionaire businessman has now said he "loves Hispanics" and employs many of them.
Cinco de Mayo, translated as 5 May, commemorates the victory of Mexican troops in a battle against French forces near the town of Puebla in 1862, and is not a wider Hispanic festival. It is also celebrated more in the US than in Mexico itself.
That did not stop Mr Trump naming it a festival for all people of Hispanic origin. Plenty of people were keen to point this out:
Democratic front-runner Hillary Clinton quickly responded to Mr Trump's tweet, pointing out that he has repeatedly said he would deport Hispanics.
With an eye on the commercial potential, restaurant chain Chipotle tweeted that their own taco bowl was probably as good as Mr Trump's.
Mexican-American comedian and actor George Lopez tweeted in reply that Mr Trump's taco bowl was probably made by undocumented immigrants - a group Mr Trump has vowed to deport.
Steven Dennis, a writer for Bloomberg, pointed out that an Eater.com review of the Trump taco bowl called it an "insult to Mexicans".
Gabe Bergado, a writer for The Daily Dot, offered up a simpler reaction.
And Jose Antonio Vargas, a Filipino American TV producer and writer, proposed an end to taco bowls altogether.
Republican front-runner Donald Trump has declared his love for tacos and Hispanics with a tweet on Mexico's Cinco De Mayo national holiday.