It capped off a superb day for the British women's number three, who came through her opening match at Wimbledon by coming from behind to beat Italy's Karin Knapp 4-6 6-4 6-0.
"I am a very, very happy girl right now. I was very, very emotional at the end, especially with (Fed Cup captain) Judy Murray. She told me that I got the wildcard for the Olympics. It was just amazing news," she said.
"I think that's why we both just started crying our eyes out. I just really want to say thanks a lot to the ITF and the committee for giving me a place. I just can't explain to you how amazing it feels, you know, all my hard work over the last so many years and, you know, all the time I have played Fed Cup. Everything has just been so, so worth it. I'm really honoured and privileged that I have been given that chance."
World number 101 Baltacha had been the favourite for her opening match against Knapp, ranked 11 spots below her, but the Italian had the Ukraine-born former British number one on the ropes as she took the opening set.
Baltacha fought back hard, however, breaking her opponent's resistance in the second set and then benefiting from an unfortunate slip by Knapp which saw her unable to compete properly thereafter.
The British player ended up crushing her opponent in the third set to earn a second-round match against defending champion Petra Kvitova, and give her one of the best days of her tennis life as she was also named on the Olympic team.
"I didn't particularly start well and she was a very tricky opponent. I managed to kind of get the second set done, and I felt like I played better, but I was struggling with the serve," said Baltacha.
"Then the third set started and I felt like I was kind of me, in a way. I played well and I fought, and I was very, very delighted to have won that and to come through that being a set down."
Serena and Venus Williams were among six players nominated for the US Olympic women's team to compete in next month's Games.
The Williams sisters were listed to play in both the Olympic singles tournament and as a team in doubles for the competition on the grass courts of the All England Lawn Tennis Club at Wimbledon.
US women's tennis coach Mary Joe Fernandez also nominated Christina McHale and Varvara Lepchenko to play singles, and the world's number one-ranked doubles team of Liezel Huber and Lisa Raymond.
Serena Williams, a 13-times grand slam singles champion, and her sister Venus are undefeated in Olympic doubles competition claiming gold medals in 2000 and 2008. Seven-time grand slam singles champion Venus Williams also won the gold in singles at the 2000 Sydney Olympics.
US men's tennis coach Jay Berger nominated a six-player team consisting of four singles entries and two doubles teams.
Former US Open champion and 2004 Olympian Andy Roddick was named on the team along with John Isner, Ryan Harrison and Donald Young in singles.
The 2008 bronze medalists in men's doubles, Bob Bryan and Mike Bryan, will return to the Olympics as a US men's doubles team, with Isner and Roddick making up a second doubles team.
The United States will also nominate two teams in mixed doubles, which will be contested at the Olympics for the first time since tennis returned to the Games in 1988. The mixed doubles teams will be made up from those on the squad and will be announced once all players are on site, the USTA said.
Baltacha added that she is expecting a tougher match in the next round against the defending champion.
"She's a very good player, very classy. She's got a fantastic game on the grass. Obviously if she plays at her best it's going to be very, very tough but you never know what can happen. If it's on Centre or No.1 Court, I'll love the opportunity to play in front of a big crowd."