However, Castro said he still faced a long and possibly risky recovery from surgery.
State television showed Castro celebrating his 80th birthday Sunday with President Hugo Chavez at his bedside.
Castro is seen talking with Mr Chavez and smiling, writing and eating yogurt in his first appearance on video since a July 31 announcement that he had undergone intestinal surgery and ceded power to his younger brother Raul, the defence minister.
Castro photos
A party newspaper also published eight similar still images of Castro.
One of the photos printed in the state-run Granma daily shows Castro dressed in a red shirt receiving a birthday gift from Chavez.
In another, he is seen posing beside a portrait of himself that Raul gave to the visiting Venezuelan president. Other pictures show him writing in a notebook, eating and shaking hands with Chavez.
The state-run daily said it was "an unforgettable afternoon between friends" and that Castro and Chavez spent three hours sharing "anecdotes, smiles, photos, gifts, a frugal snack and the joy of an intimate friendship."
"This is the best of all the visits I made in my life," Granma quoted Mr Chavez as saying.
The leftist Venezuelan president expressed admiration at Castro's recovery.
"What human being is this? What material is he made of? It is ... the copal tree," Mr Chavez said in reference to a hardwood tree that grows in Cuba.
Mr Chavez gave Castro a cup and a dagger that once belonged to South American liberation hero Simon Bolivar, and was given a portrait of Castro painted in 1959 by Mexican artist David Alfaro Siqueiros.
Castro message
In a message to the Cuban people published on Sunday, Castro made it clear that while he was recovering, he was not out of danger.
"I urge everyone to be optimistic and at the same time always prepared for any bad news there may be," he added.
After surgery, Castro had asked that his birthday celebration be postponed until December 2, the 50th anniversary of his return from exile in Mexico to topple US-backed dictator Fulgencio Batista.
But a scaled-down birthday celebration saw concerts and other events held across the country.