Former world number one Djokovic, the seven-time Wimbledon champion, needed surgery earlier this month following a serious knee injury at the French Open.
But on Friday the 37-year-old took his place in the draw for Wimbledon, which starts on Monday, with Djokovic, seeded two, taking on 123rd-ranked Vit Kopriv of the Czech Republic at the grass-court Grand Slam.
Djokovic's movement was not completely smooth in a 6-3, 6-4 win over Medvedev during an exhibition event at London's Hurlingham Club, with the Serbian's right knee strapped up. But he struck the ball crisply and served well.
"I can tell you that I enjoyed myself really, really much today," said Djokovic afterwards. "I can tell you that pain-free tennis is the best tennis. I was pain-free and I'm really glad. It was a great test obviously against one of the best players in the world.
"I've played a couple of practice sets but I really wanted to test myself. The test was very successful so I'm obviously really glad. It's been an intense three week after surgery, spending a lot of hours rehabbing."
Djokovic, whose tally of 24 singles titles at Grand Slam tournaments is the most won by any man in tennis history, added: "I kind of always wanted to give myself a chance to be in London. I think my surgeon is here. He's the MVP (most valuable player) for sure the last three weeks.
"I'm trying to take it day by day and see how far it goes."
Djokovic was forced to pull out ahead of his quarter-final at the French Open against Casper Ruud after tearing the medial meniscus in his right knee.
He has since been looking to learn from fellow tennis players and athletes who have suffered similar injuries, including American Taylor Fritz, who faced a similar situation three years ago and recovered in time for Wimbledon.
"I asked him, I asked many athletes -- (Stan) Wawrinka, (skier) Lindsey Vonn, (footballer) Zlatan Ibrahimovic -- and they were all very kind to share some of their experiences and give me some contacts of people who could help me out," said Djokovic.
