After weeks of speculation over whether he would be replaced by long-term friend Tom Wood, the player who deputised for him in Argentina last summer, the debate was over once it was guaranteed he would fit to face Australia, Argentina and New Zealand.
The 27-year-old has led England in 16 of Lancaster's 19 games in charge, missing only the final Test against South Africa in June 2012 and the June games against the Pumas.
"Chris has been in great form through the first half of this season and his experience as England captain meant it was a pretty easy decision," Lancaster said.
"I'm delighted for Chris and I'm sure he'll do a great job. My priority has always been to decide on the captain on form and fitness.
"We want a broad leadership group but when it came down to it, Chris was the standout to captain the side.
"My priority has always been to choose the captain on form and fitness.
"The first thing is to get everyone fit and in camp. If Chris had been injured on the weekend, things would have been different.
"I decided when I knew Chris was fit for the weekend and I'd had a good chance to talk to him."
Overlooked by the British and Irish Lions for Australia and rested for the trip to Argentina, the 17-times capped openside was given the summer off by Lancaster.
Wood took over the captaincy against the Pumas and acquitted himself well, creating what appeared to be a shootout for the role between the back rows.
Once Lancaster informed the duo on Monday night of who would be at the helm next month, Robshaw was assured of Wood's full support.
"Tom's been very supportive. We have a very good relationship in which we work hard and try to push each other," Robshaw said.
"A lot has been made of the captaincy but everyone in the squad is out there to achieve the same goal.
"We're a team that wants to win and be in the best possible position for 2015, whether it's myself leading the team or one of the other guys.
"It really is a core group of 10 or 11 leaders that continues to drive this squad and push it."
Robshaw was installed as England skipper for the first time in last year's RBS 6 Nations - only his second cap - and has experienced highs and lows during his reign.
"I'm not really sure (how my leadership has changed). You continue to learn in a role like this," Robshaw said.
"You learn from your experiences - the good, bad or the ugly. You have to make the most of them all."
Pressure on Robshaw's place in the team was also applied by Gloucester openside Matt Kvesic on the strength of his performances against the Pumas.
But while Kvesic's early season form dipped, partly affected by playing behind an underpowered pack at Kingsholm, Robshaw has impressed in a struggling Harlequins team.
"I was happy to let the season play out and for Chris to play well. Matt Kvesic played well at openside in the summer," Lancaster said.
"It was important for Matt to know that he has an opportunity to play, but Chris has fought him off."
Lancaster revealed that Northampton prop Alex Corbisiero is "unlikely" to recover from his knee problem in time to face Australia on November 2.