According to S&P, the higher rating is a reflection of the New York-based airline's improved financial performance.
"Our upgrade on JetBlue reflects its improved operating performance and reduced debt, which have strengthened the company's credit measures," Standard & Poor's credit analyst Betsy Snyder said in a statement.
The ratings service believes this upward trend in performance will continue "barring any negative effects from weaker-than-expected economic growth or a steep increase in fuel prices."
This is welcome news for airline that's in a period of transition.
In the early 2000s, JetBlue helped redefine budget air travel by providing premium amenities and service at a relatively a low price.
But the airline has been under competitive pressure to maintain its level of service as low-cost airlines sell tickets at rock-bottom prices and take a pass on frills.
Wall Street analysts have accused the airline of financial underperformance and a preoccupation with maintaining brand values rather than the bottom line.
Last September, after a management shakeup that saw the installation of former president Robin Hayes as JetBlue's new CEO, the stock has soared. Jetblue has also changed its product offerings. The airline will pack its passengers tighter into planes and charge for checked bags. The carrier is also rolling out a first-class offering. called "Mint," on selected routes.
Management expects that these moves will help bolster JetBlue's bottom line.