The companies declined to comment on how much of each sale goes to Target versus TRU Kids.

Starting Tuesday, shoppers who visit ToysRUs.com to buy the latest L.O.L. Surprise! dolls or Hot Wheels cars will be redirected to Target.com, to complete the purchase, once they select "buy."

The deal will allow Toys R Us to once again have an online presence, post bankruptcy, as it simultaneously begins to open Toys R Us stores in the U.S. again. And it could also be a huge boost to Target's already-strong toy business ahead of this holiday season.

Target announced on Tuesday that it's partnering with the parent company of the Toys R Us brand, TRU Kids, to help it relaunch ToysRUs.com.

You'll be able to shop at Toys R Us online again — thanks to a little help from Target.

Tru Kids CEO Richard Barry, who previously worked as chief merchandising officer at Toys R Us, said Target was ultimately tapped to power the website because of its already impressive toy business, its strong supply chain and clear "understanding of the [toy] category."

"We spoke to a lot of different folks as we went through this process," Barry said. "What inspired me about Target was their investment in the category."

He said the new site won't be just for making purchases. Instead, TRU Kids hopes ToysRUs.com will become a resource for parents looking for the latest toys to buy, and an educational tool for kids. It will have videos, top toy lists and product reviews, for example.

"We have completely reimagined [the website] ... to a site which is immersive and heavily content oriented," Barry said. "One of the things we have been working on with the initial launch is to make the site very relevant for consumers this holiday season ... with a big focus on the products we think will be magic this year."

For Target, the deal builds on its investments in the toy aisles for more than a year.

Ahead of last holiday season, Target added a quarter-million square feet of space permanently dedicated to toys across more than 500 stores. About 100 stores received a fuller remodeling in the toy aisles. When it reported 2018 holiday results, Target said same-store sales were up 5.7%, with the toy category being one of its strongest.

At the end of August, it announced a deal with Disney to open Disney stores within its own stores, exclusively selling toys, apparel and accessories. Twenty-five of those shop-in-shops opened Friday and dozens are planned for the next year.

"Toys has always been an important category for Target," said Nikhil Nayar, senior vice president of merchandising for Target. "Last year, with TRU not being in the marketplace ... we accelerated that business."

The Toys R Us deal will help "broaden our reach," Nayar said, adding that Target is "confident" it has the right inventory in place this holiday season to handle any surge in orders. One bonus, he said, will be ToysRUs.com customers who get redirected to Target to complete a purchase will then add Target items to their shopping carts.

From a supply-chain standpoint, Target is seen by retail analysts as one of the best in the business, thanks to recent investments. It acquired delivery provider Shipt for $550 million two years ago, allowing it to offer customers same-day delivery for thousands of items. Target also offers online purchasers free curbside pickup at 1,500 stores and free in-store pickup at all 1,850 U.S. Target shops.

The partnership with Target marks one of a handful that have been announced by TRU Kids.

Through a joint venture with software retailer b8ta, it will open two permanent stores next month — at Simon Property Group's The Galleria mall in Houston and at Unibail-Rodamco-Westfield's Garden State Plaza mall in Paramus, New Jersey — marking Toys R Us' return.

Toys R Us liquidated last year, forcing 800 U.S. stores to go dark. Under its new ownership, 10 Toys R Us stores are expected to open in the U.S. in 2020. Target said it will also power the online sales in those stores, should sales associates have to order any items that aren't stocked.

TRU Kids also announced last month a partnership with Candytopia, the company known for its interactive candy exhibits, as part of its efforts to revive and evolve the toy store. Ahead of this holiday season, it will open Toys R Us Adventure, "an immersive wonderland that celebrates the whimsical, silly and fun of toys," in Atlanta and in Chicago.

Following the Toys R Us bankruptcy, the company's lenders acquired the rights to the Toys R Us brand name and the iconic Geoffrey the Giraffe mascot. Tru Kids, which is managing those brands now on behalf of the toy retailer's lenders, has been trying to stage a comeback that reimagines how retailers might best take advantage of the Toys R Us legacy.

— CNBC's Lauren Hirsch contributed to this report.