Scarlets have suffered a poor season as they currently languish in 14th place in the United Rugby Championship (URC) with four wins in 15 league games.
The Llanelli-based region also lost all four matches in the European Champions Cup.
“This season has tested us but also brought the group closer together,” said Macleod.
“We’ve shown glimpses of what we’re capable of against top sides in the URC and Europe. The challenge now is turning those moments into consistency.”
The Wales flanker, who has played five internationals, hopes to return before the end of the season after suffering a hamstring injury.
“It’s been frustrating being sidelined during the last couple of weeks,” said Macleod.
“I’m not far away now and working hard to get back. Hopefully I can play my part towards the end of the season.”
Scarlets interim director of rugby Nigel Davies said Macleod was a “natural leader”.
“He drives standards and represents what we want this team to stand for,” said Davies.
“Having players like Josh at the core of Scarlets is critical. He understands what it takes to perform and help build a team.
“He leads through his actions, is brave in how he plays and has the mindset to keep pushing standards.”
