Also as reported earlier, Dutchman Robin Frijns, who worked in a similar role at Sauber last year, will be a new Caterham reserve driver.
"The process may have taken longer than we'd have liked, but we didn't want or need to be rushed into such important decisions, and we have been in the happy position of having a wide range of drivers to choose from," said team boss Cyril Abiteboul.
Japanese Kobayashi, renowned for his adrenaline-fuelled driving style, thanked his fans who pledged money to help the popular 27-year-old return to F1 after losing his Sauber seat in 2012.
"I am very pleased that the money they raised not only helped me but will now go to helping Caterham progress this year," he said.
What is also clear, however, is that drivers with more lucrative backing were overlooked by Caterham.
"This wasn't about money," said team owner Fernandes. "Having him here is a good morale boost for the team."
Entrepreneur Fernandes, who also owns the Malaysian airline Air Asia, hinted that 2014 could be Caterham's last chance to score a point and move up the F1 grid after three years as a backmarker.
"There comes a point," he admitted to Britain's Sky.
"I'm the most optimistic man in the world but you don't want to be coming last all the time. This is a very pivotal year."