The trade gives the Nuggets added depth as the team attempts to work out an agreement with guard Arron Afflalo, who is a restricted free agent. The team signed Brazilian center Nene to a five-year deal on Tuesday night. Sources close to the talks said Nene's deal is worth in excess of $67 million.
Miller and Fernandez will now be paired up again in the Mile High City.
Brewer signed with Dallas late last season and appeared in six playoff games for the NBA champs. He has averaged nearly nine points over four seasons.
"We are excited to add two talented young wing players who have proven themselves in the NBA," said Masai Ujiri, the executive vice president of basketball operations for the Nuggets. "I'm confident they will fit well with coach (George) Karl's style of play."
Fernandez has been a backup most of his NBA career, averaging 9.1 points over 24.1 minutes in 218 games. His role with the Nuggets is up in the air. Miller and Ty Lawson are looking like the starting guards at this point, especially in light of Afflalo's uncertain return.
But Fernandez's flexibility will allow Karl to find him minutes.
Fernandez never played for the Mavericks after being acquired. In fact, he finally resolved his visa issues Tuesday that had him stranded in his home country of Spain where he was playing for Real Madrid during the lockout.
"Finally I have my visa, tomorrow I'll will be on my way to Dallas," Fernandez said via Twitter on earlier Tuesday.
Fernandez, who spent the bulk of the lockout playing on a big-money contract in his native Spain, reportedly wanted to move to a new NBA team in the final year of his contract after the Mavericks acquired Lamar Odom, Vince Carter and Delonte West.
Sources say Fernandez is eager to move on in what is seen as a pivotal year for him as he decides whether to keep playing in the NBA or return to Europe.
Brewer said on his Twitter account shortly after the trade: "Man the NBA is a business I'll miss you Dallas but can't wait to get to Denver!"
Dallas had high hopes for Brewer coming into the season after using him sparingly last season, but was ultimately willing to part with him.
Brewer, entering just his fourth NBA season, joined the Mavs in mid-season and appeared in six playoff games for the NBA champs after signing a three-year contract. He got caught in a numbers crunch with the addition of veteran wings Carter and Odom. Carter will likely take over as the starting shooting guard with Odom possibly coming off the bench as a tag-team with small forward Shawn Marion.
The move wipes about $5.2 million off the books for this season, which will leave the Mavs just over the $70.3 million luxury tax threshold. It also leaves them with two roster spaces open and Dallas can now target two more veterans on minimum deals, perhaps a center such as still available free-agent big man Joel Przybilla or others. Center is Dallas' top position of need.
In the process, the Mavs continue to create additional cap space for next summer's highly anticipated free agency.
Marc Stein is a senior NBA writer for ESPN.com. Information from ESPNDallas.com's Jeff Caplan and The Associated Press was used in this report.