Perhaps as a gentle rebuke to Trump's fiery rhetoric of building walls and putting America first, Obama urged his successor to build "ladders of success" for people less fortunate and to remember the importance of American leadership in the world.
But perhaps most pointedly he reminded the 45th president - a political neophyte - of his place in the constitution and the temporary nature of his time in the White House.
"That makes us guardians of those democratic institutions and traditions - like rule of law, separation of powers, equal protection and civil liberties - that our forebears fought and bled for. Regardless of the push and pull of daily politics, it's up to us to leave those instruments of our democracy at least as strong as we found them," he wrote.
In his initial days in office, Trump thanked his predecessor for wise counsel during the run-up to the inauguration.
The relationship has soured since he accused Obama of wire-tapping Trump Tower and he has spent much of his presidency trying to overturn much of the Obama legacy.
But the Oval Office letter is a tradition that spans party divides.
When George W Bush left, he wrote to Obama: "There will be trying moments. The critics will rage. Your 'friends' will disappoint you. But, you will have an Almighty God to comfort you, a family who loves you, and a country that is pulling for you, including me."
Obama struck a similar tone as he encouraged Trump to find comfort in the people close to him.
"And finally, take time, in the rush of events and responsibilities, for friends and family. They'll get you through the inevitable rough patches," he wrote.
This article originally appeared on the Daily Telegraph.
