Ms Trump took to Twitter to highlight her successes and achievements while her older brother instead took a bizarre shot at the president-elect on Instagram.
“Remember in the Lion King when Scar cheated to win the title as king? And the pride land was overrun with the hyenas?” posted Mr Trump.
“And all of the lions lost everything they had built and maintained? Just asking. No reason.”
Meanwhile, Ms Trump wished Joe Biden “courage and strength” and said she was “excited for the future” as she leaves Washington DC for Florida.
“It has been the honour of a lifetime to serve our nation as an advisor to the president. I am so proud of what we have accomplished and excited for the future,” she wrote.
“I came to Washington to fight for American families and I leave feeling I’ve done that.
“I hope and believe that America can move forward in a positive way, acknowledge our differences and find common ground – that is how we will remain the greatest nation.”
Observers have speculated that Ms Trump may herself now run for office, with suggestions she could primary Senator Marco Rubio of Florida in 2022.
“The last four years have been an incredible journey. In travelling to nearly every American state and dozens of countries, I fell even more deeply in love with the American people,” she added.
“Thank you for all the love and support that you have shown me. I leave DC in awe of the compassion, grace and grit that exists across this nation.
“These great and strong people have reinforced my abiding faith in America.”
Ms Trump and husband Jared Kushner will not return to their hometown of New York City when their roles end on Wednesday.
Instead, they have signed a deal to lease a luxurious condominium in Miami, after spending $30 million for a plot of land on the exclusive Indian Creek “Billionaire Bunker” island.