The 27-year-old is currently in pre-season training ahead of leading the Old Deer Park outfit into battle once again. Former Scotland fly-half Gordon Ross has also been appointed vice-captain.
"I'm delighted they both accepted. Jonathan is natural leader and had a great year last season, and with Gordon helping Jonathan with his years of experience and game understanding, it's a super combination," said the former Ospreys boss.
"I'm excited to be working alongside the both of them, they have loads to offer the game and the club.
"We need to tap into their knowledge, empowering them along with the squad, to take us forward.
"London Welsh will need as much momentum moving into the new season to push on to next level."
Mills, who represented Wales at every age-grade level, is due to make his 100th league appearance against Leeds Carnegie on September 4th - the opening day of the season.
"I was chuffed when Lyn asked me to carry on as captain," added Mills.
"It's a big boost to my confidence for a coach of his experience to come in and ask me to be captain for another year.
"But although Lyn has asked me to be club captain that doesn't guarantee that I'll be playing week in, week out. I'm going to have to work as hard as anyone, if not harder, to prove that Lyn was right to pick me.
"The captaincy has always brought out the best in me. I want to lead by example on and off the pitch - that's the kind of player I am. I like to be on the front line trying to lead the way through hard work. But there are other great leaders in the squad to help me."
It will be Mills' fifth season at Old Deer Park since making the move during the 2006-07 season. The combative back-rower can boast a wealth of experience having enjoyed spells at Bath and Llanelli Scarlets, and represented the Barbarians.
"The fixtures are out and everyone is already chomping at the bit to get the jersey for the Leeds game," added Mills
"We're doing some really good conditioning work as a squad and the new boys are settling in well.
"They're starting to find their own voice within the squad and they seem like a really good bunch of lads."