If you're on the hunt for reliable ASX dividend shares to boost your income portfolio, then you may want to look at the three shares listed below.

These companies have attractive dividend yields, robust business models, and the backing of leading brokers.

Let's now take a closer look at why they could be great buys for income investors when the market reopens next week.

Challenger Ltd (ASX: CGF)

Goldman Sachs sees annuities provider Challenger as a compelling dividend investment. The broker is bullish on the company's exposure to Australia's growing superannuation market and believes rising yields should create a favourable sales environment for its retail annuities.

Goldman expects Challenger to pay fully franked dividends of 27 cents per share in FY 2025 and then 28 cents per share in FY 2026. Based on the current share price of $6.11, this implies dividend yields of 4.5% and 4.65%, respectively.

The broker has a buy rating and $7.60 price target on the stock.

Harvey Norman Holdings Limited (ASX: HVN)

Household goods retailer Harvey Norman is an ASX dividend share that Bell Potter has named as a top buy.

The broker believes the company is well positioned to benefit from an upcoming AI-driven upgrade cycle, as consumers replace devices purchased during the pandemic peak.

Bell Potter also highlights Harvey Norman's strong relationships with major brands and chip manufacturers, which give it access to exclusive product launches.

It is forecasting fully franked dividends of 25.9 cents per share in FY 2025 and then 28.5 cents per share in FY 2026. Based on the current share price of $5.34, this represents dividend yields of 4.85% and 5.3%, respectively.

The broker has a buy rating and $5.80 price target on the stock.

Smartgroup Corporation Ltd (ASX: SIQ)

Another ASX dividend share that Bell Potter is backing is Smartgroup. It is a provider of salary packaging and fleet management services.

The broker notes that the company is attractively priced, with a forward P/E of around 14.5x, a defensive client base, and tailwinds from the Electric Car Discount Bill, which exempts low- and zero-emission vehicles from Fringe Benefits Tax.

Bell Potter expects Smartgroup to pay fully franked dividends of 53.3 cents per share in FY 2024 and then 59.7 cents per share in FY 2025. Based on its current share price of $7.60, this equates to sizeable dividend yields of 7% and 7.85%, respectively.

The broker has a buy rating and a $10.00 price target on its shares.