Messi has been out of action since sustaining an ankle injury in Argentina's extra-time win over Colombia in the Copa America final on July 14.
As a result of the injury and his participation at Copa America, Messi has not featured for Inter Miami since he scored in a 3-3 draw against St Louis City on June 3.
The 37-year-old was also forced to miss Argentina's recent 2026 World Cup qualifiers against Chile and Colombia.
Messi set to return to action
Having been out of action since July, Messi is now on the verge of making his long-awaited comeback in Saturday's meeting with Philadelphia.
Martino has now revealed that Messi will be available for selection for the MLS clash at Chase Stadium in Fort Lauderdale.
"He's fine," Martino told reporters. "Yesterday he returned to training. He is contemplated for tomorrow's game and after training we will define the strategy for him, but he is available.
"We are going to once again have the best player in the world within the team so we are all happy about that situation."
Messi has shaken off illness
There was some concern that Messi's return would be delayed after he was forced to miss Wednesday's training session due to illness.
However, Martino has confirmed that the former Barcelona star made a quick recovery and has "trained normally" ahead of the weekend.
Martino added: "Yes, [there was concern] because it came together a bit with everything, the recovery of the ankle and just that throat condition he had, which prevented him from training.
"But he had been training quite well and we always thought that Philadelphia was the game to return to. Luckily, this lasted only one day. Yesterday he already trained normally, we are just simply taking into account what has happened to define the strategy for tomorrow."
Messi has registered 25 goal contributions in 15 appearances for Inter Miami this season, including 12 goals and nine assists in 12 MLS matches.
Having collected 59 points from 27 matches, Inter Miami are currently sitting in top spot in the Eastern Conference.