It means a second Games appearance for a partnership who finished ninth in Beijing and disappointment for John Pink and Rick Peacock, who were the top British boat at last year's World Championships, just missing out on the medals in fourth.
But Morrison and Rhodes, currently one place ahead of their domestic rivals in the ISAF rankings, pulled out of the World Championships after Rhodes suffered a rib injury and were the British selection at last year's Olympic test event.
And their experience, which included a bronze at the Skandia Sail for Gold regatta, held on the Olympic course, last summer - just gave them the edge.
"It does feel very different this time to four years ago – we were one of the first teams to be selected for Beijing and back then we felt like we kicked the doors down and left the selectors no scope to do anything other than select us," said Morrison.
"That led to a lot of expectation going into the Games and probably pressure on ourselves that we didn't realise at the time was there.
"This time around the things have been very different – the trials have been a lot closer but we always believed that we were the best team to deliver gold in Weymouth in 2012 and our track record in the venue over recent years supports that.
"We've learnt a lot about our sailing, about the Olympics and about ourselves since Beijing which we feel will put us in much better place to do the business at these Games."
Great Britain's 16-strong sailing team, the majority of which were announced last year, has also been completed by the selection of Games newcomer Alison Young in the women's Laser Radial.
Young beat off the challenge of Beijing Olympian Charlotte Dobson, in what was a close call for selectors.
The 24-year old was the top British finisher at last year's World Championships and is ranked fourth on the ISAF World Cup standings, just two places ahead of Dobson.
"I was pretty stunned when I found out, but it's pretty cool to be selected for an Olympic Games, and for a home Games it's even more exciting," said Young.
"There's a lot of experience on the team, and a lot of knowledge so hopefully I'll be able to tap into some of that experience to help me at my first Games.
"There's a lot of work to do now that I've been selected to push to get into the medals, and that's what I'm aiming to do, so that I can put in the best result I can.
My strengths have always been in the breeze, mostly down to my fitness and now technique as well, but my light wind game is developing and my decision-making is developing as well so I'll keep pushing those forward and hopefully the hard work in those areas will keep moving me onwards and upwards ready for the summer."
Great Britain have won 50 medals in Olympic sailing events, including 25 gold, and topped the medal table in Beijing.
"Stevie and Ben are obviously past Olympians and they have been World Championship medallists," said team leader Stephen Park.
"They were unfortunate at the World Championship in Perth that through injury they weren't able to take part. They had a great Sail for Gold Regatta on the Olympic field last summer where they medalled, and they just missed out on the medals at the Olympic test event.
"We're confident that with the experience they've got and a home venue track record, they'll be able to pull it all together and really deliver when it counts.
"With Ali Young in the Laser Radial it was a tough decision, as they all are, but as she's been the more consistent of our performers across the trials events.
"We wanted to give Ali the confidence of a selection at this stage so that she and her coach Hugh Styles can really begin to focus on the Games and build her game and her focus on the local venue."