Ethier hit his 20th homer off Dan Haren (14-8) in the first inning, a two-run single in the second and RBI doubles in the fourth and sixth as Los Angeles opened a 6-0 lead. His fifth hit was an eighth-inning single.
The win was the Dodgers' sixth in a row, a streak that began after an eight-game skid left them 4 1/2 games back of Arizona.
The Diamondbacks have dropped eight of 11.
Lowe (12-11) kept hitters off balance with his sinker. He struck out four and walked two, surrendering singles to Conor Jackson in the fourth and Chris Young in the fifth.
Chan Ho Park pitched the ninth to complete the two-hitter, the Dodgers' 11th shutout this season. Arizona has been blanked six times.
While Lowe was dominating the Diamondbacks, the Dodgers jumped on the struggling Haren, who gave up five runs and six hits in four innings.
Haren was coming off a 6-2 loss to the Dodgers last Saturday in Arizona, when he gave up five runs and 10 hits in six innings. In the right-hander's previous Dodger Stadium appearance, on April 23, he lasted just 4 2-3 innings, allowing six runs in an 8-3 loss to Lowe.
Lowe has been sharp recently, going 3-1 while allowing two or fewer runs in each of his last five starts.
For the second time in three games, Ethier came close to hitting for the cycle. After he homered, singled and hit a ground-rule double in his first three at-bats, he doubled to left-center in the sixth. When center fielder Chris Young bobbled the ball, Ethier started for third, changed his mind, and was tagged out in a rundown.
Since Young probably would have drawn an error, Ethier's hit likely wouldn't have provided the triple he needed for the cycle. He homered, singled and tripled in Los Angeles' 8-4 win over San Diego on Tuesday.
Brandon Webb will try for his 20th win for the third time when he faces Los Angeles' Chad Billingsley in the second game of the series, the final set between the teams this year unless they are tied at the end of the regular season and have a one-game playoff.
